EQUILIBRIUM GENERAL CONCEPTS

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "EQUILIBRIUM GENERAL CONCEPTS"

Transcription

1 WHEN THE REACTION IS IN EQUILIBRIUM EQUILIBRIUM GENERAL CONCEPTS The concentrations of all species remain constant over time, but both the forward and reverse reaction never cease When a system is at equilibrium, the forward and reverse reactions are proceeding at the same rate. Equilibrium is signified with double arrows or the equal sign in reaction equation. 1 The same equilibrium composition is reached from either the forward or reverse direction, provided the overall system composition is the same. Pure NO is brown and pure N O 4 is colorless. The amber color of the equilibrium mixture indicates that both species are present at the equilibrium. The decomposition of N O 4 (g) into NO (g). The concentrations of N O 4 and NO change relatively quickly at first, but eventually stop changing with time when equilibrium is reached. 4 1

2 There is a simple relationship between the concentrations of the reactants and products for any chemical system at equilibrium. It is called the mass action expression, and it is derived from thermodynamics. Consider the equilibrium: H ( g) I ( g) HI( g) Four experiments to study the equilibrium among H, I, and HI gases. Different amounts of the reactants and products are placed in a 10.0 L reaction vessel at 440 o C where the gases establish equilibrium. When equilibrium is reached, different amounts of reactants and products remain. 5 6 The numerical value of the mass action expression is called the reaction quotient, Q. [HI] Expt. [H] [I] [HI] [H ][I I II III IV Average 49.5 ] 7 The reaction quotient can be evaluated at any concentrations. [HI] Q [H ][I ] At equilibrium (and 440 o C) for the this reaction the reaction quotient has the value 49.5 (an unit less number). 8

3 The value 49.5 is called the equilibrium constant, K c, and characterizes the system [HI] o K c 49.5 (at 440 C) [H ][I ] This relationship is called the equilibrium law for the system. For chemical equilibrium to exist, the reaction quotient Q must be equal to the equilibrium constant K c. dd ee At equilibrium f [ F] [ G] d [ D] [ E] ff gg K The form is always products over reactants raised to the appropriate powers The exponents in the mass action expression are the same as the stoichiometric coefficients. g e c 9 10 QUIZ For the following reaction find the formula of K C : H + N NH a) c) b) QUIZ Given the equilibrium concentrations for the reaction below, what is the value of the equilibrium constant in terms of concentrations? A (aq) + B (aq) C (aq) + D (aq) At equlibrium: [A]= 1 M; [C]= M [B]= M; [D] = 4 M 11 1

4 SOLUTION QUIZ K C = 6 1 For the reaction below, the equilibrium constant is equal to one. Which of the these sets of equilibrium concentrations is possible? A (aq) + B (aq) 4C (aq) A) [A]= M, [B]= 1 M, [C]= 1 M B) [A]= M, [B]= M, [C]= M C) [A]= 1 M, [B]= 1 M, [C]= M D) [A]= 1 M, [B]= 1 M, [C]= 1 M 14 VARIOUS OPERATIONS CAN BE PERFORMED ON EQUILIBRIUM EXPRESSIONS Changing the direction of equilibrium Multiplying coefficients Adding chemical equilibria Changing the direction of equilibrium When the direction of an equilibrium is reversed, the new equilibrium constant is the reciprocal of the original: PCl Cl PCl 5 PCl PCl Cl 5 [ PCl5 ] Kc [ PCl ][ Cl ] K ' c [ PCl ][ Cl] 1 [ PCl ] K 5 c

5 Multiplying the coefficients by a factor When the coefficients in an equation are multiplied by a factor, the equilibrium constant is raised to a power equal to that factor; PCl Cl PCl 5 PCl PCl 5 Cl [ PCl5 ] Kc [ PCl ][ Cl ] K " c [ PCl ] [ Cl ] [ PCl 5] K c Adding chemical equilibriums When chemical equilibria are added, their equilibrium constants are multiplied N N O N O O 4O N O Adding gives : 4NO 4NO K K K c c1 c [ N O] [ N [ O ] ] [ NO ] [ N [ NO ] [ N O] 4 4 ] [ O ] 4 [ O ] K c1 K c EXAMPLE Using the equilibrium constants from Table below calculate the value of K for the reaction CaCO (s) + H + (aq) Ca + (aq) + HCO (aq) CaCO (s) Ca + (aq) + CO (aq) K 1 = 5.01 x 10 7 HCO (aq) H + (aq) + CO (aq) K = 5.01 x Solution: The net reaction is the sum of reaction 1 and the reverse of reaction : CaCO (s) Ca + (aq) + CO (aq) H + (aq) + CO (aq) HCO (aq) CaCO (s) + H + (aq) Ca + (aq) + HCO (aq) K 1 = 5.01 x

6 The magnitude of K and the position of equilibrium. LARGE K C VALUES A large amount of product and very little reactant at equilibrium gives K>>1 (large K). When K 1, approximately equal amounts of reactant and product are present at equilibrium. When K<<1, mostly reactant and very little product are present at equilibrium. Large K C value means that reaction proceeds almost completely to the rights (products are favoured, products predominate over reactants) e.g. H + O H O 1 SMALL K C Small K C value means that reaction proceeds almost completely to the lefts (reactants are favoured, reactants predominate over products) e.g. N + O NO INTERMEDIATE K C When K C has a value between 10 - and 10 it tells that at equilibrium all components of reaction are present in significant amounts, and that the equilibrium reaction is fairly evenly balanced (neither lying to the left nor to the right). e.g. H + I HI at 400 o C K C = 50.5 (reactants and products are both present in approximately equal amounts). 4 6

7 QUIZ Look at the following equilibrium constants. Do these equilibrium reactions lie to the left, to the right, or in the middle? A) H CO +H O HCO - + H O + K C = B) NO + O NO K c = C) CH 4 + H O CO + H K c = D) CH COOH + H O CH COO - + H O + K c = PREDICTING THE DIRECTION OF A REACTION aa bb cc dd Q< K C aa bb cc dd. Q> K C aa bb cc dd Q (reaction quotient) K c (equilibrium constant) Q (reaction quotient) K c (equilibrium constant) [A] and [B] decrease (must be consumed) Greater than at equilibrium [C] and [D] increase (must be formed) [A] and [B] increase must be formed Less than at equilibrium [C] and [D] decrease; must be consumed Reaction proceeds from the left to the right 7 Reaction proceeds from the right to the left 8 7

8 Q=K C The reaction quotient is the same as the equilibrium constant. The reaction is already at equilibrium, no changes in the balance between the forward and back reactions. PROBLEM TO SOLVE The concentration of the three substances in the following reaction: H + I HI are as follows: [H ] = 1.5 mol L -1 [I ] = 0.5 mol L -1 [HI] = 1 mol L -1 K C = In which direction would the reaction need to proceed for equilibrium to be reached? 9 0 SOLVING Q = < 50.5 The reaction must proceed from the left to the right (forward reaction) for equilibrium to be reached 1 TO SELF-CHECK The concentration of the three substances in the following reactions: H + I HI are as follows: [H ] = 0.05 mol L -1 [I ] = 1.05 mol L -1 [HI] = 1.9 mol L -1 K C = In which direction would the reaction need to proceed for equilibrium to be reached? 8

9 The gas law can be used to write the equilibrium constant in terms of partial pressures molarity PV nrt P n V RT MRT Equilibrium constants written in terms of partial pressures are given the symbol K p N ( g) H K c ( g) [ NH ] [ N ][ H ] NH and ( g) NH N P H The size of the equilibrium constant gives a measure of how the reaction proceeds. General statements can be made about the equilibrium constant (either K c or K P ). K P P P 4 The two different forms of the equilibrium constants can be related PV nrt P K P n K ( RT ) g n RT MRT V c n g so that where (moles of gaseous products) -(moles of gaseous reactants) QUIZ Nitrogen gas and hydrogen gas combine to form ammonia in the Haber Bosch process. What equation can be used to convert K C to K p for the Haber Bosch process N (g) + H (g) NH (g) K p = K c (RT) Δn 5 6 9

10 QUIZ CONTINUATION For the same process at 5 o C, K C =.5 x10 8. What is K p? K p = K C (RT) - K p =( ). ( ) - = In a homogeneous reactions, all the reactants and products are in the same phase. Heterogeneous reactions involve more than one phase e.g. Thermal decomposition of sodium bicarbonate (baking soda) heat NaHCO ( s) NaCO ( s) HO( g) CO ( g) Heterogeneous reactions can come to equilibrium just like homogeneous systems 9 HETEROGENOUS EQUILIBRIUM In general, equilibrium constant expressions are presented in terms of molar concentration or gas phase pressures. For pure liquids or solids, experiments have shown that: The position of the equilibrium state of a system does not depend on the amount of liquid or solid in the reaction, provided that some exists. Pure liquids and solids do not appear in the equilibrium expression

11 If NaHCO is placed in a sealed container, heterogeneous equilibrium is established NaHCO ( s) Na CO ( s) CO ( g) H O( g) The equilibrium constant is : [ NaCO ][ CO ][ H O] K [ NaHCO ] The equilibrium law involving pure liquids and pure solids can be simplified For a pure liquid or solid, the ratio of amount of substance to volume of substance is constant The concentration of a substance in a solid is constant. Doubling the number of moles doubles the volume, but the ratio of moles to volume remains the same The equilibrium law for a heterogeneous reaction is written without concentration terms for pure solids or pure liquids. K c [ CO ][ H O ] QUIZ What is the equilibrium constant expression K p for the following reaction? CO (g) + H (g) < - > CO(g) + H O(l) The equilibrium constants found in tables represent all the constants combined

12 Solution Write the equilibrium constant expression the normal way for gases, in terms of the partial pressures of each gas. The liquid water on the right hand side of the equation will not have a term in the expression, so the answer is K = P CO /P CO P H FREE GIBBS ENERGY AND EQUILIBRIUM ΔG is related to equilibrium constant K c through van t Hoff isotherm ΔG = - RT ln K c ΔG = 0 at equilibrium because both reactant and product concentrations remain constant APPLICATION OF VAN T HOFF ISOTERM 1. CO + Cl COCl ΔG = -RT ln K K = 4.57 x10 9 at 100 o C ΔG = - (8.1 J K -1 mol -1 ) (( )K) (ln 4.57 x10 9 ) = kj mol -1 ΔG is negative, so reaction occurs spontaneously, reaction lies to the right (the products predominate over the reactants) and it is energetically favourable APPLICATION OF VAN T HOFF ISOTERM. N + O NO ΔG = -RT ln K K = 4.7 x10-1 at 5 o C ΔG = - (8.1 J K -1 mol -1 ) (( )K) (ln 4.7 x10-1 ) = kj mol -1 ΔG is positive, so reaction does not occur spontaneously, reaction lies to the left (very few products form) and it is energetically unfavourable

13 According to Le Châtelier s principle: If an outside influence upsets an equilibrium, the system undergoes a change in the direction that counteracts the disturbing influence and, if possible, returns the system to equilibrium common stresses Adding or removing a product or reactant Temperature Pressure Catalyst Inert gas Adding or removing a product or reactant The equilibrium shifts to remove reactants or products that have been added. The equilibrium shifts to replace reactants or products that have been removed REACTANTS OR PRODUCTS ADD/ REMOVE A + B C + D increase the concentration of A. It means that the position of equilibrium will move so that the concentration of A decreases again - by reacting it with B and turning it into C and D. The position of equilibrium moves to the right. Decreasing A A + B C + D The position of equilibrium will move so that the concentration of A increases again. It means that more C and D will react to replace the A that has been removed. The position of equilibrium moves to the left

14 TEMPERATURE A + B C + D ΔH= -50 KJ MOL -1 Increasing the temperature shifts a reaction in a direction that produces an endothermic (heat-absorbing) change. Decreasing the temperature shifts a reaction in a direction that produces an exothermic (heat-releasing) change. This shows that 50 kj is evolved (hence the negative sign) when 1 mole of A reacts completely with moles of B. For reversible reactions, the value is always given as if the reaction was one-way in the forward direction Suppose the system is at equilibrium at 00 C, and the temperature is increasing to 500 C. How can the reaction counteracts the change it has been made? How can it cool itself down again?

15 PRESSURE/ VOLUME PRESSURE A (G) + B (G) C (G) + D (G) This only applies to reactions involving gases: A (g) + B (g) C (g) + D (g) Increasing pressure The more molecules are present in the container, the higher the pressure will be. The system can reduce the pressure by reacting in such a way as to produce fewer molecules. Decreasing pressure Producing more molecules. In this case, the position of equilibrium will move towards the left-hand side of the reaction. QG6oc Cz8Y Catalysts have no effect on the position of equilibrium Catalysts change how fast a system achieves equilibrium, not the relative distribution of reactants and products Adding an inert gas at constant volume If the added gas cannot react with any reactants or products it is inert towards the substances in the equilibrium No concentration changes occur, so Q still equals K and no shift in equilibrium occurs 59 TO SUM UP Change Concentration Pressure Temperature A (G) + B (G) C (G) + D (G) + H Effect Increasing (reactants)favours the forward reaction Decreasing (reactants)favours the back reaction Increasing (products)favours the back reaction Decreasing (products) favours the forward reaction Increasing the pressure favours the reactions which yields the smaller number of molecules Decreasing the pressure favours the reactions which yields the largest number of molecules Increasing the temperature favours the endothermic reaction Decreasing the temperature favours the exothermic reactions 60 15

16 QUIZ What properties can be changes to shift the reaction equilibrium? A) volume B) temperature C) changing the reactant or product concentration D) catalyst E) inert gas F) the true answers are. 61 QUIZ Le Chatelier's principle states that a) if a chemical system at equilibrium is stressed, the system will adjust to increase the stress b) if a chemical system at equilibrium is stressed, the system will adjust to reduce the stress c) if a chemical system at equilibrium is stressed, the system will not adjust 6 QUIZ EXAMPLE Changes in pressure will only affect substances that are in the state. a. gaseous b. liquid c. solid Predicting the Effect of Changing Volume on Gas- Phase Reactions: Predict whether a decrease in the volume of the container will drive an equilibrium system for each reaction toward more products, toward more reactants, or neither. a. NH (g) + O (g) HNO (l) + H O (l) b. CO (g) + CF 4(g) COF (g) c. C (s) + H O (g) CO (g) + H (g)

17 NH (G) + O (G) HNO (L) + H O (L) CO (G) + CF 4(G) COF (G) Decreased volume shifts the system to the side of the reaction that has fewer moles of gas. This reaction has the same number of moles of gaseous reactants and products, EQULIBRIUM CALCULATIONS C (S) + H O (G) CO (G) + H (G) Be careful with this one. Although there are the same number of moles of reactants and products, one of the reactants is a solid. Equilibrium calculations can be divided into two main categories: 1) Calculating equilibrium constants from known equilibrium concentrations or partial pressures. ) Calculating one or more equilibrium concentrations or partial pressures using the known value of K c or K P

18 If mol N O 4(g) is placed in a 1 L flask at 5 o C, at equilibrium the following concentration are present: [ N O ] 0.09 mol/l 4 [ NO ] mol/l, and [ NO ] (0.0116) Kc [ N O ] (0.09) 4 N O 4(g) NO (g) Calculating the equilibrium constant this way is easy. 69 More commonly, a set of initial conditions and an equilibrium constant are used for calculation of reagents and products concentration at equilibrium. The Initial, Change, Equilibrium or ICE table is a useful way to summarize the problem. 70 Example: Ethyl acetate, CH CO C H 5, is produced from acetic acid and ethanol by the reaction CH CO H l) C H OH( l) CH CO C H ( l) H O( ( 5 5 l At 5 o C, K c = 4.10 for this reaction. Suppose mol of ethyl acetate and mol of water are placed in a 1.00 L reaction vessel. What are the concentrations of all species at equilibrium? ANALYSIS: Use an ICE table and the equilibrium constant to find the concentrations. ) All species are in the liquid phase. Let x concentration that reacts, then I ( M ) C ( M ) CH CO H C H OH 5 CH CO C H H O x x - x - x E ( M ) x x x x ( x)( x) Kc 4.10 x x x x

19 This can be solved by putting it in quadratic form: For an equation in the form ax bx c 0, For thissystem: b x b 4ac a x x Kc 4.10 or x.10x 0.50x and x 0.11 and x Negative concentrations are not allowed, so x and at equilibriu m [ CH CO H ] x M [ C H OH] x M [ CH CO C H ] x M [ H O] x 0.011M 5 5 A similar procedure can be used to calculate partial pressures using K P 7 74 Sometime simplifications can be made Example: Nitrogen and oxygen react to form nitrogen monoxide N ( g) O ( g) NO( ) g with K c = 4.8x10-1. In air at 5 o C and 1 atm, the N concentrations and O are initially 0.0 M and M. What are the equilibrium concentrations? ANALYSIS: The equilibrium constant is very small, very little of the reactants will be converted into products 75 I ( M ) C( M ) E( M ) c N x 0.0 K x x 1 O x (x), (0.0- x)( x) NO x x 4x or x (0.0)( )

20 Substituting: [N ]=0.0-x=0.0 M [O ]= x= M [NO]=x=1.60x10-17 M THE SAME CALCULATION EQUILIBRIA IN SOLUTIONS OF WEAK ACIDS AND BASES All weak acids behave the same way in aqueous solution: they partially ionize. In terms of the general weak acid HA, this process can be written as: HA HO HO A Following the procedures K a [ HO ][ A ] [ H ][ A ] [ HA] [ HA] 79 K a is called the acid ionization constant. This is often reported as the pk a pk log a K a list the K a and pk a for a number of acids A large pk a, means a small value of K a and only a small fraction of the acid molecules ionizes A small pk a, means a large value of K a and a large fraction of the acid molecules ionizes 80 0

21 QUIZ What is the H O + concentration and ph of a 0.10 M solution of hypochlorous acid (HOCl)? Hint: K a =.5 x 10-8 HOCl + H O = H O + + OCl ANSWER x = [H O + ] = 5.9 x 10-5 = [OCl - ] (also) ph = -log[h O + ] = -log(5.9 x 10-5 ) = 4. [HOCl] = x 10-5 = 0.10 M Weak bases behave in a similar manner like acids in water For the general base B: B H O HB OH the base ionization constant is [ HB ][ OH ] Kb [ B] Values of K b and pk b for a number of weak bases are listed in special Tables. Where, like for acids: pk log b K b

22 QUIZ What is the OH - concentration and ph of a 0.05 M solution of NH? Hint: K b = 1.8 x 10-5 There is an interesting relationship between the acid and base ionization constants for a conjugate acid-base pair Using the general weak acid HA: For theweak acid : HA H O A H O the product is H O A for theconjugate base : HA OH [ HO ][ A ] [ HA][ OH ] Ka Kb [ HA] [ A ] K [ H O ][ OH ] K a [ HA][ OH ] Kb [ A ] w [ HO ][ A ] [ HA] Thus, for any conjugate acid-base pair: K K K and a pk a b pk b w pk w o (at 5 C) Most tables of ionization constants only give values for the molecular member of the conjugate acid-base pair. The ionization constant of the ion member of the conjugate acid-base pair is then calculated as needed

23 Relative strengths of conjugate acidbase pairs. The stronger the acid is, the weaker the conjugate base. The weaker the acid, the stronger the conjugate base. Very strong acids ionize 100% and their conjugate bases do not react to any measurable extent. 89 COMMON CALCULATION The primary goal is usually to determine the equilibrium concentration for all species in the mass action expression The percentage ionization of the acid or base is defined as: percentage moles ionized per liter ionization 100% moles available per liter This, and the ph, are often used or requested in equilibrium calculations 90 Example: Morphine is very effective at relieving intense pain and it is a weak base. What is the K b, pk b, and percentage ionization of morphine if a M solution has a ph of 10.10? ANALYSIS: The reaction can be represented as: I C E B( aq) H O x x BH ( aq) OH x At equilibrium, [OH - ] = x = 10 -poh 0 x 0 x x [ BH ][ OH ] Kb [ B] x x SOLUTION: Use poh = ph, substituting: [ OH ] ( ) 6 4 M, then 4 x (1. 10 ) Kb x ( so pk 5.80, and x % ionization 100% % b 4 ) 91 9

24 SIMPLIFYING ASSUMPTIONS The quadratic equation is usually used to solve equilibrium problems time consuming Simplifying assumptions : the initial concentration of a weak acid or base in pure water is more that 400 times the ionization constant C O >400* K 9 94 I C Example: Calculate the ph of a M solution of dimethylamine for which K b =9.6x10-4. ANALYSIS: 400* K b > M, so use of the quadratic equation is indicated SOLUTION: Set the problem up B( aq) H O x E x BH ( aq) OH ( aq) x 0 x 0 x x K b 4 - [ BH ][ OH ] [ B] x ( x) 95 Put in standard form x Kb ( x) ( x) K x 0 x K x K 4 7 x x Solve for x and the equilibrium concentrations Only positivesolutions are allowed, so x M 4 [ BH ] [ OH ] x M [ B] ( x) M.910 b (9.610 b 4 (1) and 4 M ) 4(1)( b 7 ) 96 4

25 BUFFERS HOW IT'S WORKING? Minimizes ph changes when a small amount of strong acid or base is added to certain solutions Buffer solution usually contains two solutes, one providing a weak acid and the other a weak base If the weak acid is molecular, then the conjugate base can be supplied as a soluble salt of the acid Consider the general buffer made so that both acid HA and salt A - are present in solution 1. When base (OH - ) is added, the weak acid react with added base: HA( aq) OH ( aq) A ( aq) HO Net result: small changes in ph HOW IT'S WORKING? Consider the general buffer made so that both acid HA and salt A - are present in solution. When acid (H + ) is added, the salt A - react with added acid A ( aq) H ( aq) HA( aq) Net result: small changes in ph CALCULATIONS INVOLVING BUFFER SOLUTIONS It is worth remembering that for buffers: the initial concentration of both the weak acid and its conjugate base can be used as though they were equilibrium values molar concentrations or moles can be used in the K a (or K b ) (the same units must be used for both members of the pair)

26 Example: What is the ph of a buffer made by adding 0.10 mol NH and 0.11 mol NH 4 Cl to.0 L of solution? The K b for ammonia is 1.8x10-5 ANALYSIS: This is a buffer, initial concentrations can be used as equilibrium values: NH ( aq) H O NH ( aq) OH ( aq) mol [ NH ] 0.050M.0 L 0.11mol [ NH 4 ] 0.055M (from NH 4Cl).0 L [ NH 4 ][ OH ] Kb [ NH ] SOLUTION: Solve for [OH - ] and use this to calculate the ph [ NH 4 ][ OH ] 5 (0.055)[ OH ] K b [ NH ] (0.050) 5 (0.050) [ OH ] poh 4.79 and ph WHAT DETERMINES THE PH OF THE BUFFER? For the general weak acid HA: HA( aq) [ H Thus both : rearrangin g gives ] K the value of K a H ( aq) A ( aq) a [ HA] or [ H [ A ] ] K mol HA mol A the ratio of the molarities (or the ratio of moles) affect the ph. [ H ][ A ] Ka [ HA] a 10 WHAT DETERMINES THE PH OF THE BUFFER? ph pk ph pk a a [ A ] log [ HA] initial [ salt] log [ acid ] initial the Henderson-Hasselbalch equation it's worth remembering!!! the ph is mostly determined by the pk a of the acid;(in buffer, the concentration ratio is usually near 1) it's worth remembering!!! or the Henderson-Hasselbalch equation it's worth remembering!!! 104 6

27 Example: A solution of 0.0 M in acetic acid (HAc) and 0.10 M in sodium acetate (NaAc) were mixed. What is the ph of new solution? ICE TABLE Compare x to the K a value. In our sample problem, the concentrations of the weak acid and its conjugate base are 10 - and the K a is The difference is greater than 100 so both of the x quantities may be ignored. ph = -log[h O + ] = -log[.6 x 10-5 ] =

28 BUFFER CAPACITY BUFFER CAPACITY The goal of a buffer is to keep the ph of a solution within a narrow range Generally, the ph change in an experiment must be limited to about 0.1pHunit Buffer capacity =the effectiveness of a buffer A buffer s capacity is determined by the magnitudes of the molarities of its components. For a useful buffer : ph pk a Example: 0.0 mol of HCl was added to a buffer made from 0.10 mol HA (pk a =7.0) and 0.15 mol NaA in.0 L with no volume change. What is the ph change? ANALYSIS: This buffer problem is best solved in terms of moles. HCl is a strong acid. The H + it contributes to solution increases the amount of HA present at the expense of A -. SOLUTION: The ph before addition of HCl was: [ A ] [ HA] final final ( ) mol 0.1 mol ( ) mol 0.1 mol the phof the new solution is : 0.1 mol ph 7.0 log 7., and the phchange is 0.1 mol ph ph ph finial initial ph p K a [ A ] 0.15 mol log 7.0 log 7.8 [ HA] 0.10 mol

29 AND IF THERE WAS NO BUFFER If the HCl had been added to pure water, the ph change would have been much larger: 0.0 ph log THANK YOU FOR YOUR KIND ATTENTION!!! 115 9

15.1 The Concept of Equilibrium

15.1 The Concept of Equilibrium Lecture Presentation Chapter 15 Chemical Yonsei University 15.1 The Concept of N 2 O 4 (g) 2NO 2 (g) 2 Chemical equilibrium occurs when a reaction and its reverse reaction proceed at the same rate. The

More information

C h a p t e r 13. Chemical Equilibrium

C h a p t e r 13. Chemical Equilibrium C h a p t e r 13 Chemical Equilibrium Chemical equilibrium is achieved when: the rates of the forward and reverse reactions are equal and the concentrations of the reactants and products remain constant

More information

Chemical Equilibrium

Chemical Equilibrium Chemical Equilibrium Many reactions are reversible, i.e. they can occur in either direction. A + B AB or AB A + B The point reached in a reversible reaction where the rate of the forward reaction (product

More information

Chemical Equilibrium. Many reactions are, i.e. they can occur in either direction. A + B AB or AB A + B

Chemical Equilibrium. Many reactions are, i.e. they can occur in either direction. A + B AB or AB A + B Chemical Equilibrium Many reactions are, i.e. they can occur in either direction. A + B AB or AB A + B The point reached in a reversible reaction where the rate of the forward reaction (product formation,

More information

Chemical Equilibrium. Chapter 8

Chemical Equilibrium. Chapter 8 Chemical Equilibrium Chapter 8 Equilibrium is a state in which there are no observable changes as time goes by. Chemical equilibrium is achieved when: the rates of the forward and reverse reactions are

More information

(i.e., equilibrium is established) leads to: K = k 1

(i.e., equilibrium is established) leads to: K = k 1 CHEMISTRY 104 Help Sheet #8 Chapter 12 Equilibrium Do the topics appropriate for your lecture http://www.chem.wisc.edu/areas/clc (Resource page) Prepared by Dr. Tony Jacob Nuggets: Equilibrium Constant

More information

CHEMISTRY XL-14A CHEMICAL EQUILIBRIA. August 20, 2011 Robert Iafe

CHEMISTRY XL-14A CHEMICAL EQUILIBRIA. August 20, 2011 Robert Iafe CHEMISTRY XL-14A CHEMICAL EQUILIBRIA August 20, 2011 Robert Iafe Unit Overview 2 Reactions at Equilibrium Equilibrium Calculations Le Châtelier s Principle Catalysts Reactions at Equilibrium 3 Reversibility

More information

Chapter 15 Chemical Equilibrium. Equilibrium

Chapter 15 Chemical Equilibrium. Equilibrium Chapter 15 Chemical The Concept of Chemical equilibrium occurs when a reaction and its reverse reaction proceed at the same rate. The Concept of As a system approaches equilibrium, both the forward and

More information

REACTION EQUILIBRIUM

REACTION EQUILIBRIUM REACTION EQUILIBRIUM A. REVERSIBLE REACTIONS 1. In most spontaneous reactions the formation of products is greatly favoured over the reactants and the reaction proceeds to completion (one direction). In

More information

EQUILIBRIA. e Q = a D B

EQUILIBRIA. e Q = a D B I. Basis of Equilibrium. A. Q and equilibrium. EQUILIBRIA 1. Consider the general reaction bb + cc dd + ee a. Αs time elapses, [B] and [C] decrease causing the rate of the forward reaction to decrease.

More information

Chapter 9. Chemical Equilibrium

Chapter 9. Chemical Equilibrium Chapter 9. Chemical Equilibrium 9.1 The Nature of Chemical Equilibrium -Approach to Equilibrium [Co(H 2 O) 6 ] 2+ + 4 Cl- [CoCl 4 ] 2- + 6 H 2 O Characteristics of the Equilibrium State example) H 2 O(l)

More information

Chemical Equilibrium. Chemical Equilibrium

Chemical Equilibrium. Chemical Equilibrium Chemical Equilibrium When some types of chemical reactions occur in the gas or solution phases, these reaction attain chemical equilibrium, i.e., the reaction does not go to completion, but the reaction

More information

1.0 L container NO 2 = 0.12 mole. time

1.0 L container NO 2 = 0.12 mole. time CHEM 1105 GAS EQUILIBRIA 1. Equilibrium Reactions - a Dynamic Equilibrium Initial amounts: = mole = 0 mole 1.0 L container = 0.12 mole moles = 0.04 mole 0 time (a) 2 In a 1.0 L container was placed 4.00

More information

Ch#13 Outlined Notes Chemical Equilibrium

Ch#13 Outlined Notes Chemical Equilibrium Ch#13 Outlined Notes Chemical Equilibrium Introduction A. Chemical Equilibrium 1. The state where the concentrations of all reactants and products remain constant with time 2. All reactions carried out

More information

Chemical Equilibrium

Chemical Equilibrium Chemical Equilibrium Concept of Equilibrium Equilibrium Constant Equilibrium expressions Applications of equilibrium constants Le Chatelier s Principle The Concept of Equilibrium The decomposition of N

More information

Dr. Valverde s AP Chemistry Class

Dr. Valverde s AP Chemistry Class AP* Chemistry Dr. Valverde s AP Chemistry Class Chapter CHEMICAL 13 Review: EQUILIBRIA: Chemical Equilibrium GENERAL CONCEPTS THE NATURE OF THE EQUILIBRIUM STATE: Equilibrium is the state where the rate

More information

January 03, Ch 13 SB equilibrium.notebook

January 03, Ch 13 SB equilibrium.notebook Ch 13: Chemical Equilibrium exists when 2 opposing reactions occur simultaneously at the same rate (dynamic rather than static) Forward rate = reverse rate https://www.youtube.com/watch?v=wld_imyqagq The

More information

CHEM N-2 November 2014

CHEM N-2 November 2014 CHEM1612 2014-N-2 November 2014 Explain the following terms or concepts. Le Châtelier s principle 1 Used to predict the effect of a change in the conditions on a reaction at equilibrium, this principle

More information

Chapter 14: Chemical Equilibrium

Chapter 14: Chemical Equilibrium Chapter 14: Chemical Equilibrium Chemical Equilibrium What does is mean to describe a chemical reaction as being in a state of dynamic equilibrium? What are the characteristics and requirements of dynamic

More information

Chemical Equilibria. OCR Chemistry A H432

Chemical Equilibria. OCR Chemistry A H432 Chemical Equilibria Chemical equilibrium is a dynamic equilibrium. Features of a dynamic equilibrium, which can only be established in a closed system (nothing added or removed): - rates of forward and

More information

Chemical Equilibrium

Chemical Equilibrium Chemical Equilibrium Chemical Equilibrium When compounds react, they eventually form a mixture of products and unreacted reactants, in a dynamic equilibrium. A dynamic equilibrium consists of a forward

More information

Chemical Equilibrium. Equilibrium Constant

Chemical Equilibrium. Equilibrium Constant Chemical Equilibrium When some types of chemical reactions occur in the gas or solution phases, these reaction attain chemical equilibrium, i.e., the reaction does not go to completion, but the reaction

More information

Ch 16. Chemical Equilibria. Law of Mass Action. Writing Equil Constant Expressions Homogeneous Equilibria. 2NO 2 (g) N 2 O 4 (g)

Ch 16. Chemical Equilibria. Law of Mass Action. Writing Equil Constant Expressions Homogeneous Equilibria. 2NO 2 (g) N 2 O 4 (g) Copyright 001 by Harcourt, Inc. All rights reserved.! Ch 16. Chemical Equilibria N O 4 (g) NO (g) The concept of equilibrium and K Writing equilibrium constant expressions Relationship between kinetics

More information

Chapter 15: Chemical Equilibrium: How Much Product Does a Reaction Really Make?

Chapter 15: Chemical Equilibrium: How Much Product Does a Reaction Really Make? Chapter 15: Chemical Equilibrium: How Much Product Does a Reaction Really Make? End-of-Chapter Problems: 15.1-15.10, 15.13-15.14, 15.17-15.91, 15.94-99, 15.10-15.103 Example: Ice melting is a dynamic process:

More information

Ch 16. Chemical Equilibria. Law of Mass Action. Writing Equil Constant Expressions Homogeneous Equilibria. 2NO 2 (g) N 2 O 4 (g) equilibrium

Ch 16. Chemical Equilibria. Law of Mass Action. Writing Equil Constant Expressions Homogeneous Equilibria. 2NO 2 (g) N 2 O 4 (g) equilibrium Copyright 001 by Harcourt, Inc. All rights reserved.! Ch 16. Chemical Equilibria N O 4 (g) NO (g) The concept of equilibrium and K Writing equilibrium constant expressions Relationship between kinetics

More information

Chemical Equilibria 2

Chemical Equilibria 2 Chemical Equilibria 2 Reading: Ch 14 sections 6-9 Homework: Chapter 14: 27*, 29*, 31, 33, 41, 43, 45, 51*, 55, 61*, 63, 67*, 69* * = important homework question Review A chemical equilibrium and its respective

More information

OFB Chapter 7 Chemical Equilibrium

OFB Chapter 7 Chemical Equilibrium OFB Chapter 7 Chemical Equilibrium 7-1 Chemical Reactions in Equilibrium 7-2 Calculating Equilibrium Constants 7-3 The Reaction Quotient 7-4 Calculation of Gas-Phase Equilibrium 7-5 The effect of External

More information

Collision Theory. Collision theory: 1. atoms, ions, and molecules must collide in order to react. Only a small number of collisions produce reactions

Collision Theory. Collision theory: 1. atoms, ions, and molecules must collide in order to react. Only a small number of collisions produce reactions UNIT 16: Chemical Equilibrium collision theory activation energy activated complex reaction rate reversible reaction chemical equilibrium law of chemical equilibrium equilibrium constant homogeneous equilibrium

More information

Lesmahagow High School AHChemistry Inorganic and Physical Chemistry Lesmahagow High School CfE Advanced Higher Chemistry

Lesmahagow High School AHChemistry Inorganic and Physical Chemistry Lesmahagow High School CfE Advanced Higher Chemistry Lesmahagow High School CfE Advanced Higher Chemistry Unit 1 Inorganic and Physical Chemistry Chemical Equilibrium 1 Dynamic Equilibrium Revision Dynamic equilibrium happens in a closed system when the

More information

Section 10. Rates of Reactions Goal: Learn how temperature, concentration, and catalysts affect the rate of reaction. Summary

Section 10. Rates of Reactions Goal: Learn how temperature, concentration, and catalysts affect the rate of reaction. Summary Chapter 10 Reaction Rates and Chemical Equilibrium Section 10. Rates of Reactions Goal: Learn how temperature, concentration, and catalysts affect the rate of reaction. Summary The rate of a reaction is

More information

Chapter 15: Chemical Equilibrium. Chem 102 Dr. Eloranta

Chapter 15: Chemical Equilibrium. Chem 102 Dr. Eloranta Chapter 15: Chemical Equilibrium Chem 102 Dr. Eloranta Equilibrium State in which competing processes are balanced so that no observable change takes place as time passes. Lift Gravity Sometimes called

More information

Characteristics of Chemical Equilibrium. Equilibrium is Dynamic. The Equilibrium Constant. Equilibrium and Catalysts. Chapter 14: Chemical Equilibrium

Characteristics of Chemical Equilibrium. Equilibrium is Dynamic. The Equilibrium Constant. Equilibrium and Catalysts. Chapter 14: Chemical Equilibrium Characteristics of Chemical Equilibrium Chapter 14: Chemical Equilibrium 008 Brooks/Cole 1 008 Brooks/Cole Equilibrium is Dynamic Equilibrium is Independent of Direction of Approach Reactants convert to

More information

Assignment 70 LE CHATELIER'S PRINCIPLE AND EQUILIBRIUM CONCENTRATIONS

Assignment 70 LE CHATELIER'S PRINCIPLE AND EQUILIBRIUM CONCENTRATIONS BACKGROUND Assignment 70 LE CHATELIER'S PRINCIPLE AND EQUILIBRIUM CONCENTRATIONS The theoretical yield calculations of prior assignments are made on the assumption that the reaction goes to completion

More information

which has an equilibrium constant of Which of the following diagrams represents a mixture of the reaction at equilibrium?

which has an equilibrium constant of Which of the following diagrams represents a mixture of the reaction at equilibrium? Chapter 9 Quiz: Chemical Equilibria 1. Which of the following statements is true regarding chemical equilibrium? I. The concentrations of reactants and products at equilibrium are constant, which means

More information

CHEMICAL EQUILIBRIUM. 6.3 Le Chatelier s Principle

CHEMICAL EQUILIBRIUM. 6.3 Le Chatelier s Principle CHEMICAL EQUILIBRIUM 6.3 Le Chatelier s Principle At the end of the lesson, students should be able to: a) State Le Chatelier s principle b) Explain the effect of the following factors on a system at equilibrium

More information

Chemical Equilibrium - Chapter 15

Chemical Equilibrium - Chapter 15 Chemical Equilibrium - Chapter 15 1. Dynamic Equilibrium a A + b B c C + d D At Equilibrium: Reaction is proceeding in both directions at the same rate. There is no net change in concentrations of reactants

More information

1B Equilibrium. 3) Equilibrium is a dynamic state At equilibrium the rate in both directions must be the same.

1B Equilibrium. 3) Equilibrium is a dynamic state At equilibrium the rate in both directions must be the same. 1B Equilibrium The equilibrium constant, K c Characteristics of the equilibrium state 1) Equilibrium can only be established in a closed system. Matter cannot be exchanged with the surroundings (this will

More information

Name AP CHEM / / Collected AP Exam Essay Answers for Chapter 16

Name AP CHEM / / Collected AP Exam Essay Answers for Chapter 16 Name AP CHEM / / Collected AP Exam Essay Answers for Chapter 16 1980 - #7 (a) State the physical significance of entropy. Entropy (S) is a measure of randomness or disorder in a system. (b) From each of

More information

AS Paper 1 and 2 Kc and Equilibria

AS Paper 1 and 2 Kc and Equilibria AS Paper 1 and 2 Kc and Equilibria Q1.When one mole of ammonia is heated to a given temperature, 50 per cent of the compound dissociates and the following equilibrium is established. NH 3(g) ½ N 2 (g)

More information

Equilibrium Simulation

Equilibrium Simulation Equilibrium Simulation Imagine the two large beakers (2000 ml) are actually the same space...we have just separated them to help us keep track of reactants and products. Imagine the size of the transfer

More information

Equilibrium and Reaction Rate

Equilibrium and Reaction Rate Equilibrium and Reaction Rate Multiple Choice Questions - Answers 1. Activation energy could be considered as the minimum energy required to do which of these? A. change the orientation of the reactant

More information

Contents and Concepts

Contents and Concepts Contents and Concepts 1. First Law of Thermodynamics Spontaneous Processes and Entropy A spontaneous process is one that occurs by itself. As we will see, the entropy of the system increases in a spontaneous

More information

B. The rate will increase by a factor of twelve. C. The rate will increase by a factor of twenty-four. D. The rate will decrease by a factor of six.

B. The rate will increase by a factor of twelve. C. The rate will increase by a factor of twenty-four. D. The rate will decrease by a factor of six. 1. If O 2 (g) disappears at a rate of 0.250 M/s at a particular moment in the reaction below, what is the rate of appearance of H 2 O(g) at the same time? C 3 H 8 (g) + 5 O 2 (g) 3 CO 2 (g) + 4 H 2 O(g)

More information

The Equilibrium State

The Equilibrium State 15.1 The Equilibrium State All reactions are reversible and under suitable conditions will reach a state of equilibrium. At equilibrium, the concentrations of products and reactants no longer change because

More information

ALE 9. Equilibrium Problems: ICE Practice!

ALE 9. Equilibrium Problems: ICE Practice! Name Chem 163 Section: Team Number: ALE 9. Equilibrium Problems: ICE Practice! (Reference: 17.5 Silberberg 5 th edition) Equilibrium Calculations: Show all work with correct significant figures. Circle

More information

Acids And Bases. H + (aq) + Cl (aq) ARRHENIUS THEORY

Acids And Bases. H + (aq) + Cl (aq) ARRHENIUS THEORY Acids And Bases A. Characteristics of Acids and Bases 1. Acids and bases are both ionic compounds that are dissolved in water. Since acids and bases both form ionic solutions, their solutions conduct electricity

More information

b. There is no net change in the composition (as long as temperature is constant).

b. There is no net change in the composition (as long as temperature is constant). CHAPTER THIRTEEN Questions 9. a. The rates of the forward and reverse reactions are equal at equilibrium. b. There is no net change in the composition (as long as temperature is constant). 10. False. Equilibrium

More information

Chapter Test A. Chapter: Chemical Equilibrium

Chapter Test A. Chapter: Chemical Equilibrium Assessment Chapter Test A Chapter: Chemical Equilibrium In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question. 1. A 15.0 ml volume

More information

CHEM J-8 June /01(a) With 3 C-O bonds and no lone pairs on the C atom, the geometry is trigonal planar.

CHEM J-8 June /01(a) With 3 C-O bonds and no lone pairs on the C atom, the geometry is trigonal planar. CHEM1001 2014-J-8 June 2014 22/01(a) What is the molecular geometry of the formate ion? Marks 7 With 3 C-O bonds and no lone pairs on the C atom, the geometry is trigonal planar. Write the equilibrium

More information

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. A) 1588 B) C) 28 D) 397 E) 0.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. A) 1588 B) C) 28 D) 397 E) 0. Chapter 15 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The value of Keq for the equilibrium 1) H2 (g) + I2 (g) 2 HI (g) is 794 at 25 C. What

More information

K w. Acids and bases 8/24/2009. Acids and Bases 9 / 03 / Ionization of water. Proton Jumping Large proton and hydroxide mobility

K w. Acids and bases 8/24/2009. Acids and Bases 9 / 03 / Ionization of water. Proton Jumping Large proton and hydroxide mobility Chapter 2 Water Acids and Bases 9 / 03 / 2009 1. How is the molecular structure of water related to physical and chemical behavior? 2. What is a Hydrogen Bond? 3Wh 3. What are Acids Aid and db Bases? 4.

More information

Homework #7 Chapter 8 Applications of Aqueous Equilibrium

Homework #7 Chapter 8 Applications of Aqueous Equilibrium Homework #7 Chapter 8 Applications of Aqueous Equilibrium 15. solution: A solution that resists change in ph when a small amount of acid or base is added. solutions contain a weak acid and its conjugate

More information

Acid Base Equilibria

Acid Base Equilibria Acid Base Equilibria Acid Ionization, also known as acid dissociation, is the process in where an acid reacts with water to produce a hydrogen ion and the conjugate base ion. HC 2 H 3 O 2(aq) H + (aq)

More information

CHEMISTRY 1AA3 Tutorial 2 Answers - WEEK E WEEK OF JANUARY 22, (i) What is the conjugate base of each of the following species?

CHEMISTRY 1AA3 Tutorial 2 Answers - WEEK E WEEK OF JANUARY 22, (i) What is the conjugate base of each of the following species? CHEMISTRY 1AA3 Tutorial 2 Answers - WEEK E WEEK OF JANUARY 22, 2001 M.A. Brook B.E. McCarry A. Perrott 1. (i) What is the conjugate base of each of the following species? (a) H 3 O + (b) NH 4 + (c) HCl

More information

Name period AP Unit 8: equilibrium

Name period AP Unit 8: equilibrium Name period AP Unit 8: equilibrium 1. What is equilibrium? Rate of the forward reaction equals the rate of the reverse reaction 2. How can you tell when equilibrium has been reached? The concentrations

More information

Chapter 15 Equilibrium

Chapter 15 Equilibrium Chapter 15. Chemical Equilibrium Sample Exercise 15.1 (p. 632) Write the equilibrium expression for K eq for these three reactions: a) 2 O 3(g) 3 O 2(g) b) 2 NO (g) + Cl 2(g) 2 NOCl (g) c) Ag + (aq) +

More information

Thermodynamic Connection

Thermodynamic Connection Slide 1 Thermodynamic Connection Q and G and letters other than K Slide 2 Reaction Quotient What do you call an equilibrium constant when you aren t at equilibrium? A Reaction Quotient! (Q) Slide 3 Consider

More information

Ch. 17 Applications of Aqueous Equilibria: Buffers and Titrations

Ch. 17 Applications of Aqueous Equilibria: Buffers and Titrations Ch. 17 Applications of Aqueous Equilibria: Buffers and Titrations Sec 1 The Common-Ion Effect: The dissociation of a weak electrolyte decreases when a strong electrolyte that has an ion in common with

More information

7. The coffee cup allows for pv work because it allows for a change in volume.

7. The coffee cup allows for pv work because it allows for a change in volume. 1. A black body radiator is a theoretically perfect body that absorbs all energy incident upon it (or produced within it) and then emits 100% of this energy as electromagnetic radiation. 2. First, it is

More information

Acid-Base Equilibria. 1.NH 4 Cl 2.NaCl 3.KC 2 H 3 O 2 4.NaNO 2. Acid-Ionization Equilibria. Acid-Ionization Equilibria

Acid-Base Equilibria. 1.NH 4 Cl 2.NaCl 3.KC 2 H 3 O 2 4.NaNO 2. Acid-Ionization Equilibria. Acid-Ionization Equilibria Acid-Ionization Equilibria Acid-Base Equilibria Acid ionization (or acid dissociation) is the reaction of an acid with water to produce hydronium ion (hydrogen ion) and the conjugate base anion. (See Animation:

More information

Exam 2 Sections Covered: (the remaining Ch14 sections will be on Exam 3) Useful Information Provided on Exam 2:

Exam 2 Sections Covered: (the remaining Ch14 sections will be on Exam 3) Useful Information Provided on Exam 2: Chem 101B Study Questions Name: Chapters 12,13,14 Review Tuesday 2/28/2017 Due on Exam Thursday 3/2/2017 (Exam 2 Date) This is a homework assignment. Please show your work for full credit. If you do work

More information

Chemistry 1A, Spring 2007 Midterm Exam 3 April 9, 2007 (90 min, closed book)

Chemistry 1A, Spring 2007 Midterm Exam 3 April 9, 2007 (90 min, closed book) Chemistry 1A, Spring 2007 Midterm Exam 3 April 9, 2007 (90 min, closed book) Name: KEY SID: TA Name: 1.) Write your name on every page of this exam. 2.) This exam has 34 multiple choice questions. Fill

More information

5.1 Module 1: Rates, Equilibrium and ph

5.1 Module 1: Rates, Equilibrium and ph 5.1 Module 1: Rates, Equilibrium and ph 5.1.1 How Fast? The rate of reaction is defined as the change in concentration of a substance in unit time Its usual unit is mol dm 3 s 1 When a graph of concentration

More information

ph + poh = 14 G = G (products) G (reactants) G = H T S (T in Kelvin)

ph + poh = 14 G = G (products) G (reactants) G = H T S (T in Kelvin) JASPERSE CHEM 210 PRACTICE TEST 3 VERSION 2 Ch. 17: Additional Aqueous Equilibria Ch. 18: Thermodynamics: Directionality of Chemical Reactions Key Equations: For weak acids alone in water: [H + ] = K a

More information

Chapter Test B. Chapter: Chemical Equilibrium. following equilibrium system? 2CO(g) O 2 (g) ^ 2CO 2 (g)

Chapter Test B. Chapter: Chemical Equilibrium. following equilibrium system? 2CO(g) O 2 (g) ^ 2CO 2 (g) Assessment Chapter Test B Chapter: Chemical Equilibrium PART I In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question. 1. What is

More information

3. Indicate the mass action expression for the following reaction: 2X(g) + Y(g) 3W(g) + V(g) a) [X] 2 [Y][W] 3 [V] [W] 3 [V] [X] 2 [Y] [3W][V] [2X][Y]

3. Indicate the mass action expression for the following reaction: 2X(g) + Y(g) 3W(g) + V(g) a) [X] 2 [Y][W] 3 [V] [W] 3 [V] [X] 2 [Y] [3W][V] [2X][Y] 1. Which of the following statements concerning equilibrium is not true? a) A system that is disturbed from an equilibrium condition responds in a manner to restore equilibrium. b) Equilibrium in molecular

More information

IB Chemistry ABS Introduction An acid was initially considered a substance that would produce H + ions in water.

IB Chemistry ABS Introduction An acid was initially considered a substance that would produce H + ions in water. IB Chemistry ABS Introduction An acid was initially considered a substance that would produce H + ions in water. The Brønsted-Lowry definition of an acid is a species that can donate an H + ion to any

More information

CHEMICAL EQUILIBRIA. Dynamic Equilibrium Equilibrium involves reversible reactions which do not go to completion.

CHEMICAL EQUILIBRIA. Dynamic Equilibrium Equilibrium involves reversible reactions which do not go to completion. CHEMICAL EQUILIBRIA Dynamic Equilibrium Equilibrium involves reversible reactions which do not go to completion. If we consider a reaction between A and B to form C and D which is reversible. When A and

More information

Le Chatelier's principle

Le Chatelier's principle Le Chatelier's principle Any factor that can affect the rate of either the forward or reverse reaction relative to the other can potentially affect the equilibrium position. The following factors can change

More information

Case Study: The Industrial Manufacture of Ammonia The Haber Process

Case Study: The Industrial Manufacture of Ammonia The Haber Process Case Study: The Industrial Manufacture of Ammonia The Haber Process In the Haber Process, ammonia (NH3) is synthesised from nitrogen and hydrogen gases: N 2 (g) + 3H 2 (g) Ý 2NH3(g), ΔH = 92.4 kjmol -1

More information

Chapter 16. Thermodynamics. Thermochemistry Review. Calculating H o rxn. Predicting sign for H o rxn. Creative Commons License

Chapter 16. Thermodynamics. Thermochemistry Review. Calculating H o rxn. Predicting sign for H o rxn. Creative Commons License Chapter 16 Thermodynamics GCC CHM152 Creative Commons License Images and tables in this file have been used from the following sources: OpenStax: Creative Commons Attribution License 4.0. ChemWiki (CC

More information

CH 302 Spring 2008 Worksheet 4 Answer Key Practice Exam 1

CH 302 Spring 2008 Worksheet 4 Answer Key Practice Exam 1 CH 302 Spring 2008 Worksheet 4 Answer Key Practice Exam 1 1. Predict the signs of ΔH and ΔS for the sublimation of CO 2. a. ΔH > 0, ΔS > 0 b. ΔH > 0, ΔS < 0 c. ΔH < 0, ΔS > 0 d. ΔH < 0, ΔS < 0 Answer:

More information

Operational Skills. Operational Skills. The Common Ion Effect. A Problem To Consider. A Problem To Consider APPLICATIONS OF AQUEOUS EQUILIBRIA

Operational Skills. Operational Skills. The Common Ion Effect. A Problem To Consider. A Problem To Consider APPLICATIONS OF AQUEOUS EQUILIBRIA APPLICATIONS OF AQUEOUS EQUILIBRIA Operational Skills Calculating the common-ion effect on acid ionization Calculating the ph of a buffer from given volumes of solution Calculating the ph of a solution

More information

AP Chemistry Chapter 16 Assignment. Part I Multiple Choice

AP Chemistry Chapter 16 Assignment. Part I Multiple Choice Page 1 of 7 AP Chemistry Chapter 16 Assignment Part I Multiple Choice 1984 47. CH 4 (g) + 2 O 2 (g) CO 2 (g) + 2 H 2 O(l) H = 889.1 kj H f H 2 O(l) = 285.8 kj mol 1 H f CO 2 (g) = 393.3 kj mol 1 What is

More information

Chemical Kinetics and Equilibrium

Chemical Kinetics and Equilibrium Chemical Kinetics and Equilibrium 1 Which statement incorrectly describes a chemical reaction approaching equilibrium? As a chemical reaction approaches equilibrium, the net change in the amount of reactants

More information

CHM 1046 FINAL REVIEW

CHM 1046 FINAL REVIEW CHM 1046 FINAL REVIEW Prepared & Presented By: Marian Ayoub PART I Chapter Description 6 Thermochemistry 11 States of Matter; Liquids and Solids 12 Solutions 13 Rates of Reactions 18 Thermodynamics and

More information

Intermolecular Forces 2 nd Semester Review Questions and Problems

Intermolecular Forces 2 nd Semester Review Questions and Problems Intermolecular Forces 2 nd Semester Review Questions and Problems 1. Complete the following table: Molecule Lewis Structure Molecule Shape Polar/Nonpolar CS 2 H 3 O + CdBr 2 CHI 3 2. What makes the dipole

More information

6. Which expression correctly describes the equilibrium constant for the following reaction? 4NH 3 (g) + 5O 2 (g) 4NO(g) + 6H 2 O(g)

6. Which expression correctly describes the equilibrium constant for the following reaction? 4NH 3 (g) + 5O 2 (g) 4NO(g) + 6H 2 O(g) 1. Which of the following can we predict from an equilibrium constant for a reaction? 1. The extent of a reaction 2. Whether the reaction is fast or slow 3. Whether a reaction is exothermic or endothermic

More information

TECHNICAL SCIENCE DAS12703 ROZAINITA BT. ROSLEY PUSAT PENGAJIAN DIPLOMA UNVERSITI TUN HUSSEIN ONN MALAYSIA

TECHNICAL SCIENCE DAS12703 ROZAINITA BT. ROSLEY PUSAT PENGAJIAN DIPLOMA UNVERSITI TUN HUSSEIN ONN MALAYSIA TECHNICAL SCIENCE DAS12703 ROZAINITA BT. ROSLEY PUSAT PENGAJIAN DIPLOMA UNVERSITI TUN HUSSEIN ONN MALAYSIA ii TABLE OF CONTENTS TABLE OF CONTENTS... i LIST OF FIGURES... iii Chapter 1... 4 SOLUTIONS...

More information

Practice Test - Chapter 13, 14, 15

Practice Test - Chapter 13, 14, 15 Practice Test - Chapter 13, 14, 15 1. For which of the following values of the equilibrium constant does the reaction go the farthest to completion? a. 10 5 b. 10 3 c. 10 0 d. 10-3 e. 10-5 2. Carbon disulfide

More information

REACTION RATES AND EQUILIBRIUM

REACTION RATES AND EQUILIBRIUM Name Date Class 18 REACTION RATES AND EQUILIBRIUM SECTION 18.1 RATES OF REACTION (pages 541 547) This section explains what is meant by the rate of a chemical reaction. It also uses collision theory to

More information

Equilibrium Calculations

Equilibrium Calculations OpenStax-CNX module: m51112 1 Equilibrium Calculations OpenStax College This work is produced by OpenStax-CNX and licensed under the Creative Commons Attribution License 4.0 By the end of this section,

More information

CH302 Spring 2009 Practice Exam 1 (a fairly easy exam to test basic concepts)

CH302 Spring 2009 Practice Exam 1 (a fairly easy exam to test basic concepts) CH302 Spring 2009 Practice Exam 1 (a fairly easy exam to test basic concepts) 1) Complete the following statement: We can expect vapor pressure when the molecules of a liquid are held together by intermolecular

More information

Create assignment, 48975, Exam 2, Apr 05 at 9:07 am 1

Create assignment, 48975, Exam 2, Apr 05 at 9:07 am 1 Create assignment, 48975, Exam 2, Apr 05 at 9:07 am 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page find all choices before making your selection.

More information

Chemistry 112, Spring 2007 Prof. Metz Exam 2 Solutions April 5, 2007 Each question is worth 5 points, unless otherwise indicated

Chemistry 112, Spring 2007 Prof. Metz Exam 2 Solutions April 5, 2007 Each question is worth 5 points, unless otherwise indicated Chemistry 11, Spring 007 Prof. Metz Exam Solutions April 5, 007 Each question is worth 5 points, unless otherwise indicated 1. A proposed mechanism for the reaction of NO with Br to give BrNO is NO + NO

More information

Unit F FR Practice General Equilibrium (pg 1 of 26)

Unit F FR Practice General Equilibrium (pg 1 of 26) Unit F FR Practice General Equilibrium (pg 1 of 26) 1. Answer the following questions about glucose, C6H12O6, an important biochemical energy source. (a) Write the empirical formula of glucose. In many

More information

School of Chemistry, University of KwaZulu-Natal, Howard College Campus, Durban. CHEM191 Tutorial 1: Buffers

School of Chemistry, University of KwaZulu-Natal, Howard College Campus, Durban. CHEM191 Tutorial 1: Buffers School of Chemistry, University of KwaZulu-Natal, Howard College Campus, Durban CHEM191 Tutorial 1: Buffers Preparing a Buffer 1. How many moles of NH 4 Cl must be added to 1.0 L of 0.05 M NH 3 to form

More information

Chemistry 12 Unit 2: Dynamic Equilibrium. KEY Unit 2 Problem Set A KEY

Chemistry 12 Unit 2: Dynamic Equilibrium. KEY Unit 2 Problem Set A KEY Chemistry 12 Unit 2: Dynamic Equilibrium KEY Unit 2 Problem Set A KEY 1. Water is boiling in a kettle at 100 C. Is the system at equilibrium? Explain. No. The system is not closed. 2. Ice and water are

More information

Unit 7: Chemical Kinetics and Equilibrium UNIT 7: CHEMICAL KINETICS AND EQUILIBRIUM

Unit 7: Chemical Kinetics and Equilibrium UNIT 7: CHEMICAL KINETICS AND EQUILIBRIUM UNIT 7: CHEMICAL KINETICS AND EQUILIBRIUM Chapter 19: Reaction Rates and Equilibrium 19.1: Rates of Reaction Reaction Rates: - the speed of which the concentration of a reactant or product changes over

More information

5.2 Energy. N Goalby chemrevise.org Lattice Enthalpy. Definitions of enthalpy changes

5.2 Energy. N Goalby chemrevise.org Lattice Enthalpy. Definitions of enthalpy changes 5.2 Energy 5.2.1 Lattice Enthalpy Definitions of enthalpy changes Enthalpy change of formation The standard enthalpy change of formation of a compound is the energy transferred when 1 mole of the compound

More information

Equilibrium Reversible Reactions

Equilibrium Reversible Reactions 1 Equilibrium Reversible Reactions Oak Park High School Mrs. Kornelsen Chemistry 40s Intro: Do Blue bottle Reaction demo Or watch online: http://www.dlt.ncssm.edu/core/chapter14- Gas_Phase- Solubility-

More information

Bond C=O C H C O O H. Use the enthalpy change for the reaction and data from the table to calculate a value for the H H bond enthalpy.

Bond C=O C H C O O H. Use the enthalpy change for the reaction and data from the table to calculate a value for the H H bond enthalpy. Many chemical processes release waste products into the atmosphere. Scientists are developing new solid catalysts to convert more efficiently these emissions into useful products, such as fuels. One example

More information

Chapter 1 The Atomic Nature of Matter

Chapter 1 The Atomic Nature of Matter Chapter 1 The Atomic Nature of Matter 1-1 Chemistry: Science of Change 1-2 The Composition of Matter 1-3 The Atomic Theory of Matter 1-4 Chemical Formulas and Relative Atomic Masses 1-5 The Building Blocks

More information

Energy Changes, Reaction Rates and Equilibrium. Thermodynamics: study of energy, work and heat. Kinetic energy: energy of motion

Energy Changes, Reaction Rates and Equilibrium. Thermodynamics: study of energy, work and heat. Kinetic energy: energy of motion Energy Changes, Reaction Rates and Equilibrium Thermodynamics: study of energy, work and heat Kinetic energy: energy of motion Potential energy: energy of position, stored energy Chemical reactions involve

More information

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Exam Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Which one of the following is the weakest acid? 1) A) HF (Ka = 6.8 10-4) B) HNO2 (Ka

More information

ACIDS AND BASES. HCl(g) = hydrogen chloride HCl(aq) = hydrochloric acid HCl(g) H + (aq) + Cl (aq) ARRHENIUS THEORY

ACIDS AND BASES. HCl(g) = hydrogen chloride HCl(aq) = hydrochloric acid HCl(g) H + (aq) + Cl (aq) ARRHENIUS THEORY ACIDS AND BASES A. CHARACTERISTICS OF ACIDS AND BASES 1. Acids and bases are both ionic compounds that are dissolved in water. Since acids and bases both form ionic solutions, their solutions conduct electricity

More information

Equilibrium point of any reaction is characterized by a single number: K eq is the equilibrium constant for the reaction

Equilibrium point of any reaction is characterized by a single number: K eq is the equilibrium constant for the reaction Lecture 19 Equilibrium Constant Equilibrium oint of any reaction is characterized by a single number: K eq is the equilibrium constant for the reaction In general: ja + kb R + qs K eq [ R] [ S] [ A] [

More information

SCH4U: EXAM REVIEW. 2. Which of the following has a standard enthalpy of formation of 0 kj mol -1 at 25ºC and 1.00 atm?

SCH4U: EXAM REVIEW. 2. Which of the following has a standard enthalpy of formation of 0 kj mol -1 at 25ºC and 1.00 atm? SCH4U_08-09 SCH4U: EXAM REVIEW 1. The heat of a reaction is equal to: a. enthalpy (products) + enthalpy (reactants) b. enthalpy (reactants) enthalpy (products) c. enthalpy (products) enthalpy (reactants)

More information

All reversible reactions reach an dynamic equilibrium state.

All reversible reactions reach an dynamic equilibrium state. 11. Equilibrium II Many reactions are reversible + 3 2 All reversible reactions reach an dynamic equilibrium state. Dynamic equilibrium occurs when forward and backward reactions are occurring at equal

More information

CHEMISTRY 102 EXAM 2 SECTIONS /10/2004

CHEMISTRY 102 EXAM 2 SECTIONS /10/2004 2005 PECK Form C page1 CHEMISTRY 102 EXAM 2 SECTIONS 530-541 3/10/2004 NAME FORM C Directions: (1) Print your name. (2) Choose the best answer for the multiple choice questions (number 1-15). Transfer

More information