Assignment 70 LE CHATELIER'S PRINCIPLE AND EQUILIBRIUM CONCENTRATIONS

Size: px
Start display at page:

Download "Assignment 70 LE CHATELIER'S PRINCIPLE AND EQUILIBRIUM CONCENTRATIONS"

Transcription

1 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 (100% reaction) as described by the chemical equation. Many reactions do indeed occur essentially 100%; such reactions undergird classical quantitative analysis and are favored for synthesizing chemical substances. The quantitative calculations are focused on the amount of limiting reagent available for the reaction, because the reaction will proceed only until the limiting reagent is exhausted. The opposite situation also can occur, where chemical species do not react at all. These chemical "spectators" remain totally unchanged in a mixture. Spectator species are regularly excluded from equations of chemical reactions, since they do not participate in any chemical changes. Now in the present Assignment we come to yet a third type of situation: reactions that proceed only part way. Ultimately a major quantity of each reactant continues to remain in the final mixture, because the reactions are reversible. That is to say, the reactions proceed in both directions - forward (from reactants to products) and also in reverse (from products to reactants) with both directions occurring simultaneously. Eventually a condition is reached where the opposing reactions are exactly counter-balanced a state of dynamic equilibrium in which there is no net change. At equilibrium the forward and reverse reactions continue to occur as a dynamic system; but since the reactions exactly oppose each other, there is no net change in the amount of any substance present. The study of chemical equilibrium (the topic of this present Assignment) is concerned with describing the final condition where exact counterbalance occurs for reversible reactions. Many chemical reactions fit into this third category, and they are of great importance in chemistry. It may seem strange that a chemist should focus much attention upon reactions that may occur to a very slight extent only 5% or 1% or even less. But there is a profound difference between a species that reacts to a slight extent and one that does not react at all. In the qual scheme, for example, it is the minute differences in solubility of various insoluble compounds which provide the basis of many separations; and mild reagents such as acetic acid and ammonia derive their acidity and basicity from only slight reactivity with water. Reversible reactions are signified by use of double arrows between reactants and products, instead of a onedirectional arrow. For example: H (g) + I (g) HI (g) at a 00 o C temperature. For any specified reaction at a specific temperature, the equilibrium condition can be explicitly described by means of an equilibrium constant, K, whose value is a particular ratio of concentrations of the species involved in reaction. Several conventions are followed when defining the K for a specified reaction: By convention, molar concentrations of species are usually represented by means of brackets, [ ], placed around the formula of the species such as [H ] for the molar concentration of hydrogen gas. Also by convention, in the defining of the K, the bracketed concentrations are arranged so that the products appear in the numerator and the reactants appear in the denominator. The balanced chemical equation for the specified reaction serves as the crucial (and convenient) guide for deducing the proper arrangement

2 Example: For the chemical reaction specified above, K = [ HI] [ H ] [ I ] Note carefully the conventions used in the expressing of the K relationship above: The brackets denote molar concentration (units: M, in mol/liter) specifically the molar concentration of the chemical species whose formula appears inside the brackets. Thus, [HI] is intended to mean (moles of HI gas molecules) / liter. Reactants of the reaction always appear in the denominator; the concentrations are multiplied together in the K expression. Products of the reaction always appear in the numerator. In this particular reaction, two particles of the same kind are formed (HI and HI). Multiplying those concentrations, [HI] [HI], is the same as squaring the concentration, [HI]. (See also examples below.) The numerical value of the K is referred to as the equilibrium constant. The mathematical expression, which shows the mathematical arrangement of the concentrations, is called the equilibrium constant expression, or K expression. One further convention should be mentioned here, because the example above involves gases. For equilibria involving gaseous species (only), it is often more convenient to express the concentrations of gases in terms of the pressure of the gas, inasmuch as pressure (p) and molar concentration (n/v) for an ideal gas are directly related by the ideal gas equation. (That is, since pv = nrt for any ideal gas, a simple rearrangement shows that p = (n/v)rt at any specified temperature.) Therefore: When gas concentrations are expressed as atm pressures, then by convention the K is subscripted by p and we write K p (rather than a mere K), so as to proclaim that the definition is made in terms of gas pressures rather than molar concentrations. Accordingly, for the gaseous chemical reaction (specified above) we have the option of writing: K p = ( phi ) ( p ) ( p ) H I Note that the value of the constant, K p, presumes that all gas pressures are expressed in atmosphere dimensional units. Note also that the value of the K and the K p may differ from each other because of the different dimensional units involved but each constant will indeed be a constant value whenever the reaction is at dynamic equilibrium.) From thermodynamic reasoning, it is possible to obtain a more precise derivation of K expressions; a precise definition requires use of the activity of the substances, rather than molar concentration. But in the present course we shall neglect activities and the slight improvement they provide in calculations. Rather, the symbol K will presume a definition based on molar concentrations. (Some chemistry texts prefer to adopt a subscripted symbol, K c, for constants based on molar concentrations, instead of merely K. By subscripting both symbols, K p and K c, they differentiate the definitions more explicitly.)

3 In summary then: If the species in a reaction are gases and all concentrations are expressed as atm pressure values, the equilibrium constant will be designated by K p. Otherwise, it will be assumed that the concentrations are expressed as mol/l values as in the original definition above and the equilibrium constant will be designated by K or, in some textbooks, by K c.) More examples: 1) For a reaction having a balanced equation of this form: A + B X + Y when at equilibrium at a certain temperature, the following relationship is met: [ X ] [ Y ] K = = a constant value A B [ ] [ ] In this example, the molecules A, B, X, and Y all have different formulas, such as in the chemical reaction O 3 + NO NO + O. ) If a balanced reaction has this form of equation: A + B X + 3 Y the equation may be rewritten this way: A + A + B X + Y + Y + Y from which, at equilibrium: K = [ X ] [ Y ] [ Y ] [ Y ] [ ] [ A] [ B] = [ ] [ ] 3 X Y [ A] [ B] A In this final form of the equilibrium constant expression, note particularly the correspondence between the coefficients in the equation for the chemical reaction and the exponents in the K expression. POSITION OF EQUILIBRIUM, AND LE CHATELIER'S PRINCIPLE Every reversible reaction has associated with it an equilibrium constant. The value of the K must be achieved whenever the reaction attains equilibrium. Since the equilibrium constant is some number, the equilibrium concentrations of all substances in a reversible reaction must have numerical values such that, when multiplied and divided as indicated in the equilibrium constant expression, the equilibrium constant's number is obtained. The reaction is considered to be at equilibrium only when the set of concentrations yields the appropriate equilibrium value for the K. Any set of concentrations which yields a correct K value, for a specified reversible reaction, is considered a position of equilibrium. Such a position of equilibrium can be altered by making a change in various factors involved in the reaction. The effect of imposing a change upon an equilibrium system may be predicted (in a qualitative way) by the Principle of Le Chatelier. For reversible chemical reactions, this principle may be stated as follows: Any change (or stress) in a reversible reaction at equilibrium will cause a net chemical reaction to occur in either the forward or the reverse direction in order to counteract some of the change

4 Whenever a system at equilibrium receives a stress, which alters the balanced state, then a net chemical reaction will occur to re-attain equilibrium anew. In the net reaction the concentration of each substance may change; but, when the new equilibrium is reached, the new concentrations must be such that the same numerical constant, K, is obtained. The value of the equilibrium constant, K, does not change as long as the temperature remains constant. A reversible reaction is always written as: Reactants Products The forward direction is always considered from left to right, or from reactants to products. If the stress causes a net chemical reaction in the forward direction, relatively more products become present, and the equilibrium shifts to the right. If the stress causes a net chemical reaction in the reverse direction, relatively less products become present and the equilibrium shifts to the left. However extensive any such net reaction may be, it is always possible to specify the relative amounts of change that occur the comparative increases and decreases of individual substances by reference to the balanced chemical equation for the reaction. 1) Concentration. Examples of stresses which affect the equilibrium position If the concentration of any substance in a reversible reaction becomes suddenly altered, Le Chatelier's Principle indicates that the reaction direction is favored which undoes some of the alteration. Thus, if a substance is added as to increase its concentration, the direction is favored which uses up some of the added substance. Or, if the concentration of a substance is suddenly decreased, the direction is favored which forms the substance. A concentration may be increased by adding more of the substance, or a concentration may be decreased by removing some of the substance. (Usually the removal is achieved by adding some different substance not a part of the reversible reaction which removes the substance by means of a different chemical reaction; or, if the substance is volatile, by boiling or heating the reaction mixture until the volatile substance has been driven off as a gas, and then re-cooling to the original temperature.) It is important to remember that concentration depends both on amount and on volume, and care must be taken to account for both of these factors when a change is made. In which direction will the equilibria below be shifted, as a consequence of these stresses? Example (a): NO (g) + O (g) NO (g) If the concentration of NO is increased? (i.e., putting in more NO but not changing the volume) With more moles of NO per liter, net reaction will occur to the right, to use up some of the added reactant, NO, and to form more product, NO ; equilibrium shifts to the right. If the concentration of O is increased? Also causes a shift to the right

5 If the concentration of either NO or O is decreased? If the concentration of NO is increased? - Causes a shift to the left. Causes a net reaction to the left, to use up some of the NO ; equilibrium shifts to the left. If the concentration of NO is decreased? Causes a shift to the right. Example (b): CuSO 4 5H O (s) CuSO 4 (s) + 5 H O (g) (At a high temperature, H O vapor is formed.) If the concentration of gaseous H O is decreased? Causes a net reaction to the right, to replenish some of the lost H O more products are formed; equilibrium shifts to right. In this reaction, the brilliant blue solid, CuSO 4 5H O, is converted into a nearly white solid product, CuSO 4. (The applied stress removal of H O might be done by adding a drying agent e.g., CaCl which absorbs the water vapor, or by using an open container so that H O vapor is lost by diffusion out from the volume of the container.) If merely a pure solid is added? (e.g., adding more of the pure solid CuSO 4 reagent) Causes no shift, because the solid is a separate pure phase, therefore the concentration of the phase is not altered by the addition. Regardless of the quantity of pure solid, the solid's concentration doesn't change. ) Pressure (which has special significance for gases). The concentration of a gas is related to its partial pressure. The partial pressure of a gaseous substance is defined as the pressure that the substance would have if it were the only substance in the container (i.e, the pressure exerted by the substance, itself, upon the container). For a mixture of gases, then, the total pressure in the container is the sum of the partial pressures of each component in the mixture. Thus, the total pressure exerted upon a mixture may effect an equilibrium by influencing the partial pressure of each gas involved. Pressure affects a reaction's equilibrium only if gases are involved in the reaction. (Concentrations of liquids and solids are not significantly affected by pressure.) Since the pressure in a container depends on the number of molecules of gas in the container, Le Chatelier's Principle shows that if total pressure is increased, the equilibrium shifts in the direction giving fewer total molecules of gas (thus relieving the total pressure somewhat); or if total pressure is decreased, the equilibrium shifts to give more total molecules of gas

6 In which direction will these equilibria be shifted, in consequence of the following stresses? Example (a): At 300 o C, N (g) + 3 H (g) NH 3 (g) The equation shows that moles of gaseous products correspond to 4 moles of gaseous reactants or in terms of molecules, every molecules of NH 3 formed during a forward reaction require depletion of 4 molecules of gaseous reactants (a net decrease of molecules). Vice versa for the reverse reaction. Therefore: If the total pressure is increased? (i.e., by constriction of the volume) Causes net reaction to occur to the right, to decrease the total number of gas molecules; equilibrium shifts to the right. If the total pressure is decreased? Causes the equilibrium to shift to the left. Example (b): At 0 o C, N O 4 (l) NO (g) moles of gaseous products correspond to no moles of gaseous reactant. (Note that the reactant is a liquid at 0 o C and thus is ignored). Therefore: If the total pressure is increased? - Causes net reaction to the left, to yield fewer gas molecules; equilibrium shifts to the left. If the total pressure is decreased? Causes equilibrium to shift to the right (more gas molecules). Ignore all liquids and solids whenever you are predicting the direction of an equilibrium shift caused by pressure change. Example (c): H (g) + I (g) HI (g) moles of gaseous reactants correspond to moles of gaseous products. Therefore: If the total pressure is changed? The pressure causes no shift in this equilibrium. Example (d): CaCO 3 (s) CaO (s) + CO (g) If the total pressure is increased? If the total pressure is decreased? Equilibrium shifts to the left (toward less gas). Equilibrium shifts to the right (toward more gas)

7 3) Temperature. In order to change the temperature, heat must either be added into the system (to increase the temperature) or be removed (to decrease the temperature). Therefore, the H value associated with the equation for the reversible reaction becomes of significance in judging how the equilibrium will shift. The thermodynamic definition of H will be treated in Chem 11. For our purposes here, a positive H implies a reaction that consumes heat and a negative H implies a reaction that liberates heat. Suppose that the reversible reaction is: A + B X + Y ; H = 35 kj The equation indicates that, in the forward direction, the reaction liberates heat (a negative H value): i.e., A + B X + Y ; H = 35 kj But in the reverse direction, the reaction will require that same amount of heat (opposite H sign): i.e., X + Y A + B ; H = +35 kj. Or a different reaction: if the forward direction requires heat, its reverse direction will liberate that heat. For any given reversible reaction, Le Chatelier's Principle indicates that an increase in temperature favors the direction which requires heat (i.e., the system counteracts the added heat by using up some of it, in whichever direction requires heat); a decrease in temperature favors the direction which liberates heat. In which direction will these equilibria below be shifted, in consequence of the stated stresses? Example (a): SO (g) + O (g) SO 3 (g) ; H = 193 kj The negative H value indicates that heat energy is liberated by the system whenever reaction occurs in the forward direction, forming products of lower enthalpy than the reactants. Reaction in the reverse direction requires that heat energy come into the system. Therefore: If the temperature is increased? Net reaction occurs to the left (the direction requiring heat), thereby using up some of the added heat and forming reactants that have higher enthalpy; the equilibrium shifts to the left. If the temperature is decreased? Equilibrium shifts to right (the direction liberating heat); products at lower enthalpy. (Note: The 193 kj value for H is the value which net reaction in the forward direction has i.e., the value if exactly moles of SO 3 are made from exactly moles of SO and 1 mole of O.)

8 Change of the temperature does change the numerical value of the equilibrium constant, K ; however, the net effect on the equilibrium constant can be predicted just as above. In example (a), when the temperature rises the shift in equilibrium to the left implies that the numerical value of K for this reversible reaction must be decreasing as the temperature rises. For, at the higher temperatures, all products decrease in concentration and all reactants increase in concentration; therefore, conc. products K = conc. reactants will have a smaller value By similar reasoning, also, the value of this K becomes larger whenever the temperature decreases. Example (b): H (g) + I (s) HI (g) ; H = +5.3 kj If the temperature is increased? If the temperature is decreased? Equilibrium shifts to the right. Equilibrium shifts to the left. Effect on the numerical value of the K? The K will increase as temperature is increased, and will decrease as temperature is decreased. Example (c): A + B X + Y ; H = 0 kj (a rare situation) Changing the temperature has no effect upon this equilibrium, nor upon the equilibrium constant K for the reaction. EXPRESSING SOLUTION SPECIES IN K EXPRESSIONS IN BRACKETED STYLE One of the skills that has been emphasized in the "Formulas and Reactions" discussions is the ability to take a bulk formula and deduce the ultimate species that are present. In the case of ionic substances, these species are different from the bulk formula (i.e., for NaCl, the species actually present are Na + and Cl! ). This distinction becomes of major importance when dealing with K expressions, since any K expression is concerned with reactant and products at the individual particle level, NOT at the bulk level. Thus when you write a K expression (some ratio of amounts of products to reactants) it is amounts of ultimate species that have to be expressed, NOT bulk species. Many K expressions involve species dissolved in water. In such K expressions, amounts of all species are expressed in molarities. To save time and space we use brackets, [ ], placed around the formula of the ultimate species, to mean "concentration of, expressed in moles/liter". Thus, [Na + ] means "the molarity of sodium ion". The technique of taking a bulk formula and "translating" it into bracketed amounts of species actually present is illustrated below. This is a skill which needs to be mastered. In the examples below, the answers are given with explanations of the reasoning process

9 Examples: ("Translate" these data into bracketed style.) a) 1. M NaHCO 3? The ultimate units are Na + and HCO 3. Thus this formula is "translated" as [ Na + ] = 1. M, and [ HCO 3 ] = 1. M (The ultimate units are the ions of the metal/non-metal compound; the anion typically includes the hydrogen atom as an inherent part of the anionic ultimate unit.) b) 0.1 M Ca(OAc)? The ultimate units are Ca + and OAc. Thus this formula is "translated" as [ Ca + ] = 0.1 M, and [ OAc ] = 0. M (The ultimate units are the ions of the metal/non-metal compound, calcium ion and acetate ion. The 0.1 mol per liter of the bulk reagent, Ca(OAc), provides 0.1 mol per liter of the Ca + ultimate unit and also 0. mol per liter of the OAc ultimate unit. In solution the ions exist as separate units, not grouped together into neutral Ca(OAc) units.) c) 0.50 M (NH 4 ) SO 4? Is "translated" as [ NH 4 + ] = 1.00 M, and [ SO 4 ] = 0.50 M (The presence of these ions should be obvious; note the relative abundances.) d) 3 M H 3 PO 4? Here the ultimate unit is the formula itself and therefore should be "translated" as [ H 3 PO 4 ] = approximately 3 M (Phosphoric acid is known to be a weak acid, occurring in solution mostly as non-ionized molecules. So, by far, the predominant ultimate species will be the non-ionized H 3 PO 4 molecule. At equilibrium, ionized species such as H 3 O + and H PO 4 will occur in small amounts, formed by the ionizing of a slight amount of the H 3 PO 4 solute in the water solution; but the concentrations of those ions will be not nearly as great as 3 M. Most of the phosphoric acid will remain as non-ionized molecules to provide the 3 M concentration of that non-ionized ultimate species.) e).5 M HI? Is "translated" as [ H 3 O + ] =.5 M, and [ I ] =.5 M (Recall see the listing in the F&R manual that HI is one of the few hydrogen compounds which, when dissolved in water, becomes entirely ionized (a strong acid). At equilibrium in water, [ HI ] = 0 (there are NOT ANY ultimate species remaining in the form of non-ionized HI molecules)

10 Note that bracketed formulas are "species specific". A bracketed formula refers to the molarity of only the ultimate species specified within the bracket and of no other variety of species. Any species having a different formula would need a separate bracketed formula and has a separate molarity value of its own. The 3 M H 3 PO 4 solution in example (d) can serve to illustrate this subtlety. As stated above, the solute in this solution occurs mostly as non-ionized H 3 PO 4 molecules, but a tiny amount of the solute will be present as ionized species (in minor quantity), such as H PO 4 ions. The "translated" statement [ H 3 PO 4 ] = approx. 3 M accounts for all of the ultimate species H 3 PO 4 (i.e., all of the non-charged molecules) present. The concentration value of [ H 3 PO 4 ] is evident because that ultimate species, H 3 PO 4, is known to be, by far, the most abundant solute species in a 3 M H 3 PO 4 solution but it does NOT represent any of the ionized fragments (such as H PO 4 ions) which are also present in minor amounts in the solution. The value of [ H 3 PO 4 ] excludes all those other species. The concentration of H PO 4 ions in the solution would have a separate, tiny but distinct, value symbolized as [ H PO 4 ]. But the value of that molarity is NOT self-evident from the overall given data, since, of the 3 M H 3 PO 4 sample, only an undeclared, slight amount will occur ionized that way at equilibrium. Therefore, no value is deduced for it in this assignment. (The H PO 4 ions are considered a "minor constituent" within the solution. In a 3 M H 3 PO 4 solution, the actual value of [ H PO 4 ] would be less than 0.1 M.)

Chapter 15. Chemical Equilibrium

Chapter 15. Chemical Equilibrium Chapter 15. Chemical Equilibrium 15.1 The Concept of Equilibrium Consider colorless frozen N 2 O 4. At room temperature, it decomposes to brown NO 2. N 2 O 4 (g) 2NO 2 (g) At some time, the color stops

More information

Chapter 15 Chemical Equilibrium

Chapter 15 Chemical Equilibrium Chapter 15 Chemical Chemical 15.1 The Concept of 15.2 The Constant (K) 15.3 Understanding and Working with Constants 15.4 Heterogeneous Equilibria 15.5 Calculating Constants 15.6 Applications of Constants

More information

Chapter 15. Chemical Equilibrium

Chapter 15. Chemical Equilibrium Chapter 15. Chemical Equilibrium 15.1 The Concept of Equilibrium Consider colorless frozen N 2 O 4. At room temperature, it decomposes to brown NO 2. N 2 O 4 (g) 2NO 2 (g) At some time, the color stops

More information

Chapter 15 Equilibrium

Chapter 15 Equilibrium Chapter 15. Chemical Equilibrium Common Student Misconceptions Many students need to see how the numerical problems in this chapter are solved. Students confuse the arrows used for resonance ( )and equilibrium

More information

Chapter 15 Equilibrium

Chapter 15 Equilibrium Chapter 15. Chemical Equilibrium 15.1 The Concept of Equilibrium Chemical equilibrium is the point at which the concentrations of all species are constant. A dynamic equilibrium exists when the rates of

More information

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

Chapter 15 Equilibrium

Chapter 15 Equilibrium Chapter 15. Chemical Equilibrium Common Student Misconceptions Many students need to see how the numerical problems in this chapter are solved. Students confuse the arrows used for resonance ( )and equilibrium

More information

The Concept of Equilibrium

The Concept of Equilibrium Chemical Equilibrium The Concept of Equilibrium Sometimes you can visually observe a certain chemical reaction. A reaction may produce a gas or a color change and you can follow the progress of the reaction

More information

Chemical Equilibrium-A Dynamic Equilibrium

Chemical Equilibrium-A Dynamic Equilibrium CHAPTER 14 Page 1 Chemical Equilibrium-A Dynamic Equilibrium When compounds react, they eventually form a mixture of products and (unreacted) reactants, in a dynamic equilibrium Much like water in a U-shape

More information

EQUILIBRIUM GENERAL CONCEPTS

EQUILIBRIUM GENERAL CONCEPTS 017-11-09 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

More information

15/04/2018 EQUILIBRIUM- GENERAL CONCEPTS

15/04/2018 EQUILIBRIUM- GENERAL CONCEPTS 15/04/018 EQUILIBRIUM- GENERAL CONCEPTS When a system is at equilibrium, the forward and reverse reactions are proceeding at the same rate. The concentrations of all species remain constant over time,

More information

Equilibrium. What is equilibrium? Hebden Unit 2 (page 37 69) Dynamic Equilibrium

Equilibrium. What is equilibrium? Hebden Unit 2 (page 37 69) Dynamic Equilibrium Equilibrium What is equilibrium? Hebden Unit (page 37 69) Dynamic Equilibrium Hebden Unit (page 37 69) Experiments show that most reactions, when carried out in a closed system, do NOT undergo complete

More information

Shifting Equilibrium. Section 2. Equilibrium shifts to relieve stress on the system. > Virginia standards. Main Idea. Changes in Pressure

Shifting Equilibrium. Section 2. Equilibrium shifts to relieve stress on the system. > Virginia standards. Main Idea. Changes in Pressure Section 2 Main Ideas Equilibrium shifts to relieve stress on the system. Some ionic reactions seem to go to completion. Common ions often produce precipitates. > Virginia standards CH.3.f The student will

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

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

Chemical Equilibrium. Foundation of equilibrium Expressing equilibrium: Equilibrium constants Upsetting equilibrium Le Chatelier

Chemical Equilibrium. Foundation of equilibrium Expressing equilibrium: Equilibrium constants Upsetting equilibrium Le Chatelier Chemical Equilibrium Foundation of equilibrium Expressing equilibrium: Equilibrium constants Upsetting equilibrium Le Chatelier Learning objectives Write equilibrium constant expressions for both solutions

More information

Chem 116 POGIL Worksheet - Week 7 Kinetics to Equilibrium

Chem 116 POGIL Worksheet - Week 7 Kinetics to Equilibrium Chem 116 POGIL Worksheet - Week 7 Kinetics to Equilibrium Why? Most chemical reactions are reversible. This means that once products are formed, they can react to reform the reactants. If we allow a reaction

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

AP Chem Chapter 12 Notes: Gaseous Equilibrium

AP Chem Chapter 12 Notes: Gaseous Equilibrium AP Chem Chapter 12 Notes: Gaseous Equilibrium Equilibrium I. Equilibrium is reached when both the and reactions are occurring at. A. Dynamic Equilibrium: reactions are still occurring but the of reactants

More information

Lecture Presentation. Chapter 15. Chemical Equilibrium. James F. Kirby Quinnipiac University Hamden, CT Pearson Education

Lecture Presentation. Chapter 15. Chemical Equilibrium. James F. Kirby Quinnipiac University Hamden, CT Pearson Education Lecture Presentation Chapter 15 Chemical James F. Kirby Quinnipiac University Hamden, CT The Concept of N 2 O 4 (g) 2 NO 2 (g) Chemical equilibrium occurs when a reaction and its reverse reaction proceed

More information

Chemical Kinetics and

Chemical Kinetics and Chemical Kinetics and Equilibrium Part 2: Chemical Equilibrium David A. Katz Department of Chemistry Pima Community College Tucson, AZ USA The Concept of Equilibrium Kinetics applies to the speed of a

More information

The Mole. Relative Atomic Mass Ar

The Mole. Relative Atomic Mass Ar STOICHIOMETRY The Mole Relative Atomic Mass Ar Relative Molecular Mass Mr Defined as mass of one atom of the element when compared with 1/12 of an atom of carbon-12 Some Ar values are not whole numbers

More information

Chapter 13. The Concept of Equilibrium. A System at Equilibrium. The Concept of Equilibrium. Chemical Equilibrium. N 2 O 4 (g) 2 NO 2 (g)

Chapter 13. The Concept of Equilibrium. A System at Equilibrium. The Concept of Equilibrium. Chemical Equilibrium. N 2 O 4 (g) 2 NO 2 (g) PowerPoint to accompany The Concept of Equilibrium Chapter 13 Chemical Equilibrium Figure 13.1 Chemical equilibrium occurs when a reaction and its reverse reaction proceed at the same rate. The Concept

More information

The. Equilibrium. Constant. Chapter 15 Chemical Equilibrium. The Concept of Equilibrium. The Concept of Equilibrium. A System at Equilibrium

The. Equilibrium. Constant. Chapter 15 Chemical Equilibrium. The Concept of Equilibrium. The Concept of Equilibrium. A System at Equilibrium The Concept of Chapter 15 Chemical AP Chemistry 12 North Nova Education Centre 2017 Chemical equilibrium occurs when a reaction and its reverse reaction proceed at the same rate. The Concept of As a system

More information

Le Châtelier's Principle. Chemical Equilibria & the Application of Le Châtelier s Principle to General Equilibria. Using Le Châtelier's Principle

Le Châtelier's Principle. Chemical Equilibria & the Application of Le Châtelier s Principle to General Equilibria. Using Le Châtelier's Principle Chemical Equilibria & the Application of Le Châtelier s Principle to General Equilibria CHEM 107 T. Hughbanks Le Châtelier's Principle When a change is imposed on a system at equilibrium, the system will

More information

The Equilibrium State. Chapter 13 - Chemical Equilibrium. The Equilibrium State. Equilibrium is Dynamic! 5/29/2012

The Equilibrium State. Chapter 13 - Chemical Equilibrium. The Equilibrium State. Equilibrium is Dynamic! 5/29/2012 Chapter 13 - Chemical Equilibrium The Equilibrium State Not all chemical reactions go to completion; instead they attain a state of equilibrium. When you hear equilibrium, what do you think of? Example:

More information

2 EQUILIBRIUM 2.1 WHAT IS EQUILIBRIUM? 2.2 WHEN IS A SYSTEM AT EQUILIBRIUM? 2.3 THE EQUILIBRIUM CONSTANT

2 EQUILIBRIUM 2.1 WHAT IS EQUILIBRIUM? 2.2 WHEN IS A SYSTEM AT EQUILIBRIUM? 2.3 THE EQUILIBRIUM CONSTANT 2 EQUILIBRIUM 2.1 WHAT IS EQUILIBRIUM? In general terms equilibrium implies a situation that is unchanging or steady. This is generally achieved through a balance of opposing forces. In chemistry equilibrium

More information

CH 221 Chapter Four Part II Concept Guide

CH 221 Chapter Four Part II Concept Guide CH 221 Chapter Four Part II Concept Guide 1. Solubility Why are some compounds soluble and others insoluble? In solid potassium permanganate, KMnO 4, the potassium ions, which have a charge of +1, are

More information

AP CHEMISTRY NOTES 8-1 CHEMICAL EQUILIBRIUM: AN INTRODUCTION

AP CHEMISTRY NOTES 8-1 CHEMICAL EQUILIBRIUM: AN INTRODUCTION AP CHEMISTRY NOTES 8-1 CHEMICAL EQUILIBRIUM: AN INTRODUCTION Chemical Equilibrium a dynamic state in which the rate of the forward reaction and the rate of the reverse reaction in a system are equal (the

More information

Chapter 6: Chemical Equilibrium

Chapter 6: Chemical Equilibrium Chapter 6: Chemical Equilibrium 6.1 The Equilibrium Condition 6.2 The Equilibrium Constant 6.3 Equilibrium Expressions Involving Pressures 6.4 The Concept of Activity 6.5 Heterogeneous Equilibria 6.6 Applications

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

AP Chapter 14: Chemical Equilibrium & Ksp

AP Chapter 14: Chemical Equilibrium & Ksp AP Chapter 14: Chemical Equilibrium & Ksp Warm-Ups (Show your work for credit) Name Date 1. Date 2. Date 3. Date 4. Date 5. Date 6. Date 7. Date 8. AP Chapter 14: Chemical Equilibrium & Ksp 2 Warm-Ups

More information

2nd- Here's another example of a reversible reaction - dissolving salt in a beaker of water, described by the following reaction: NaCl (s)

2nd- Here's another example of a reversible reaction - dissolving salt in a beaker of water, described by the following reaction: NaCl (s) CHEMICAL EQUILIBRIUM AP Chemistry (Notes) Most chemical processes are reversible. Reactants react to form products, but those products can also react to form reactants. Examples of reversible reactions:

More information

AP* Chapter 13. Chemical Equilibrium

AP* Chapter 13. Chemical Equilibrium AP* Chapter 13 Chemical Equilibrium Section 13.1 The Equilibrium Condition Chemical Equilibrium The state where the concentrations of all reactants and products remain constant with time. On the molecular

More information

Chemistry B11 Chapter 5 Chemical reactions

Chemistry B11 Chapter 5 Chemical reactions Chapter 5 Chemical reactions Chemical reactions are classified into five groups: A + B AB Synthesis reactions (Combination) H + O H O AB A + B Decomposition reactions (Analysis) NaCl Na +Cl A + BC AC +

More information

Review Sheet 6 Math and Chemistry

Review Sheet 6 Math and Chemistry Review Sheet 6 Math and Chemistry The following are some points of interest in Math and Chemistry. Use this sheet when answering these questions. Molecular Mass- to find the molecular mass, you must add

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

Q.1 Write out equations for the reactions between...

Q.1 Write out equations for the reactions between... 1 CHEMICAL EQUILIBRIUM Dynamic Equilibrium not all reactions proceed to completion some end up with a mixture of reactants and products this is because some reactions are reversible; products revert to

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

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

Solubility Rules See also Table 4.1 in text and Appendix G in Lab Manual

Solubility Rules See also Table 4.1 in text and Appendix G in Lab Manual Ch 4 Chemical Reactions Ionic Theory of Solutions - Ionic substances produce freely moving ions when dissolved in water, and the ions carry electric current. (S. Arrhenius, 1884) - An electrolyte is a

More information

IB Chemistry Solutions Gasses and Energy

IB Chemistry Solutions Gasses and Energy Solutions A solution is a homogeneous mixture it looks like one substance. An aqueous solution will be a clear mixture with only one visible phase. Be careful with the definitions of clear and colourless.

More information

UNIT 11 Practice Test Page 1 of 13 Equilibrium

UNIT 11 Practice Test Page 1 of 13 Equilibrium UNIT 11 Practice Test Page 1 of 13 Do NOT write on this test. $0.10/page lost or damaged fee. 1. In which of the following does the reaction go farthest to completion? A. K = 10 5 B. K = 10 5 C. K = 1000

More information

NC Standards. NC Standards Chm Infer the shift in equilibrium when a stress is applied to a chemical system (LeChatelier s).

NC Standards. NC Standards Chm Infer the shift in equilibrium when a stress is applied to a chemical system (LeChatelier s). Equilibrium and Le Chatelier s Principle NC Standards Chm.3.1. Explain the conditions of a system at equilibrium. A. Define chemical equilibrium for reversible reactions. B. Distinguish between equal rates

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

Chemical Equilibrium. Chapter

Chemical Equilibrium. Chapter Chemical Equilibrium Chapter 14 14.1-14.5 Equilibrium Equilibrium is a state in which there are no observable changes as time goes by. Chemical equilibrium is achieved when: 1.) the rates of the forward

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

Chapter 7 An Introduction to Chemical Reactions. An Introduction to Chemistry by Mark Bishop

Chapter 7 An Introduction to Chemical Reactions. An Introduction to Chemistry by Mark Bishop Chapter 7 An Introduction to Chemical Reactions An Introduction to Chemistry by Mark Bishop Chapter Map Chemical Reaction A chemical change or chemical reaction is a process in which one or more pure substances

More information

Chapter 18. Reversible Reactions. A chemical reaction in which the products can react to re-form the reactants is called a reversible reaction.

Chapter 18. Reversible Reactions. A chemical reaction in which the products can react to re-form the reactants is called a reversible reaction. Section 1 The Nature of Chemical Equilibrium Reversible Reactions A chemical reaction in which the products can react to re-form the reactants is called a reversible reaction. Section 1 The Nature of Chemical

More information

CHEMICAL EQUILIBRIUM. Chapter 15

CHEMICAL EQUILIBRIUM. Chapter 15 Chapter 15 P a g e 1 CHEMICAL EQUILIBRIUM Examples of Dynamic Equilibrium Vapor above a liquid is in equilibrium with the liquid phase. rate of evaporation = rate of condensation Saturated solutions rate

More information

Unit 7 Kinetics and Thermodynamics

Unit 7 Kinetics and Thermodynamics 17.1 The Flow of Energy Heat and Work Unit 7 Kinetics and Thermodynamics I. Energy Transformations A. Temperature 1. A measure of the average kinetic energy of the particles in a sample of matter B. Heat

More information

CHEM 101A EXAM 1 SOLUTIONS TO VERSION 1

CHEM 101A EXAM 1 SOLUTIONS TO VERSION 1 CHEM 101A EXAM 1 SOLUTIONS TO VERSION 1 Multiple-choice questions (3 points each): Write the letter of the best answer on the line beside the question. Give only one answer for each question. B 1) If 0.1

More information

Chemical Equilibrium

Chemical Equilibrium Chemical Equilibrium THE NATURE OF CHEMICAL EQUILIBRIUM Reversible Reactions In theory, every reaction can continue in two directions, forward and reverse Reversible reaction! chemical reaction in which

More information

Chapter 6: Chemical Equilibrium

Chapter 6: Chemical Equilibrium Chapter 6: Chemical Equilibrium 6.1 The Equilibrium Condition 6. The Equilibrium Constant 6.3 Equilibrium Expressions Involving Pressures 6.4 The Concept of Activity 6.5 Heterogeneous Equilibria 6.6 Applications

More information

Chemistry I Practice Exam

Chemistry I Practice Exam Chemistry I Practice Exam Name Multiple Choice: Choose the best answer that completes each statement. Put all answers on your answer sheet. 1. The mass of one mole of NaCl is a..53 g b. 22.99 g c. 5.44

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

ENTHALPY, INTERNAL ENERGY, AND CHEMICAL REACTIONS: AN OUTLINE FOR CHEM 101A

ENTHALPY, INTERNAL ENERGY, AND CHEMICAL REACTIONS: AN OUTLINE FOR CHEM 101A ENTHALPY, INTERNAL ENERGY, AND CHEMICAL REACTIONS: AN OUTLINE FOR CHEM 101A PART 1: KEY TERMS AND SYMBOLS IN THERMOCHEMISTRY System and surroundings When we talk about any kind of change, such as a chemical

More information

2. Write a balanced chemical equation which corresponds to the following equilibrium constant expression.

2. Write a balanced chemical equation which corresponds to the following equilibrium constant expression. Practice Problems for Chem 1B Exam 1 Chapter 14: Chemical Equilibrium 1. Which of the following statements is/are CORRECT? 1. For a chemical system, if the reaction quotient (Q) is greater than K, products

More information

Chapter 3: Solution Chemistry (For best results when printing these notes, use the pdf version of this file)

Chapter 3: Solution Chemistry (For best results when printing these notes, use the pdf version of this file) Chapter 3: Solution Chemistry (For best results when printing these notes, use the pdf version of this file) Section 3.1: Solubility Rules (For Ionic Compounds in Water) Section 3.1.1: Introduction Solubility

More information

Unit 10 Solution Chemistry 1. Solutions & Molarity 2. Dissolving 3. Dilution 4. Calculation Ion Concentrations in Solution 5. Precipitation 6.

Unit 10 Solution Chemistry 1. Solutions & Molarity 2. Dissolving 3. Dilution 4. Calculation Ion Concentrations in Solution 5. Precipitation 6. Unit 10 Solution Chemistry 1. Solutions & Molarity 2. Dissolving 3. Dilution 4. Calculation Ion Concentrations in Solution 5. Precipitation 6. Formula, Complete, Net Ionic Equations 7. Qualitative Analysis

More information

Chemistry 123: Physical and Organic Chemistry Topic 4: Gaseous Equilibrium

Chemistry 123: Physical and Organic Chemistry Topic 4: Gaseous Equilibrium Topic 4: Introduction, Topic 4: Gaseous Equilibrium Text: Chapter 6 & 15 4.0 Brief review of Kinetic theory of gasses (Chapter 6) 4.1 Concept of dynamic equilibrium 4.2 General form & properties of equilbrium

More information

Chapter 4. Reactions in Aqueous Solution

Chapter 4. Reactions in Aqueous Solution Chapter 4. Reactions in Aqueous Solution 4.1 General Properties of Aqueous Solutions A solution is a homogeneous mixture of two or more substances. A solution is made when one substance (the solute) is

More information

Exam 2. CHEM Spring Name: Class: Date:

Exam 2. CHEM Spring Name: Class: Date: CHEM-112-01 Spring 2012 Name: Class: Date: 1. Record your name and ID number on the scantron form. 2. Record the test ID letter in the top right box of the scantron form. 3. Record all of your answers

More information

(Unit -9) Chemical Equilibrium

(Unit -9) Chemical Equilibrium UNIT 9 Chemical Equilibrium INTRODUCTION: We owe our existence to equilibrium phenomenon taking place in atmosphere. We inhale oxygen and exhale carbon dioxide, while plants consume carbon dioxide and

More information

Experiment 7: SIMULTANEOUS EQUILIBRIA

Experiment 7: SIMULTANEOUS EQUILIBRIA Experiment 7: SIMULTANEOUS EQUILIBRIA Purpose: A qualitative view of chemical equilibrium is explored based on the reaction of iron(iii) ion and thiocyanate ion to form the iron(iii) thiocyanate complex

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

Chapter 4. Chemical Quantities and Aqueous Reactions

Chapter 4. Chemical Quantities and Aqueous Reactions Lecture Presentation Chapter 4 Chemical Quantities and Aqueous Reactions Reaction Stoichiometry: How Much Carbon Dioxide? The balanced chemical equations for fossilfuel combustion reactions provide the

More information

Reaction Rate. Products form rapidly. Products form over a long period of time. Precipitation reaction or explosion

Reaction Rate. Products form rapidly. Products form over a long period of time. Precipitation reaction or explosion Reaction Rate Products form rapidly Precipitation reaction or explosion Products form over a long period of time Corrosion or decay of organic material Chemical Kinetics Study of the rate at which a reaction

More information

The Concept of Equilibrium

The Concept of Equilibrium The Concept of Equilibrium Reversible reactions As the concentrations of the reactants decrease the rate of reaction in the forward direction decreases. As the concentrations of the products increase the

More information

Chapter 9: Acids, Bases, and Salts

Chapter 9: Acids, Bases, and Salts Chapter 9: Acids, Bases, and Salts 1 ARRHENIUS ACID An Arrhenius acid is any substance that provides hydrogen ions, H +, when dissolved in water. ARRHENIUS BASE An Arrhenius base is any substance that

More information

Unit 6 Kinetics and Equilibrium.docx

Unit 6 Kinetics and Equilibrium.docx 6-1 Unit 6 Kinetics and Equilibrium At the end of this unit, you ll be familiar with the following: Kinetics: Reaction Rate Collision Theory Reaction Mechanism Factors Affecting Rate of Reaction: o Nature

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

2.0 Equilibrium Constant

2.0 Equilibrium Constant 2.0 Equilibrium Constant When reactions are reversible and chemical equilibrium is reached, it is important to recognize that not all of the reactants will be converted into products. There is a mathematical

More information

aa + bb ---> cc + dd

aa + bb ---> cc + dd 17 Chemical Equilibria Consider the following reaction: aa + bb ---> cc + dd As written is suggests that reactants A + B will be used up in forming products C + D. However, what we learned in the section

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

Understanding the shapes of acid-base titration curves AP Chemistry

Understanding the shapes of acid-base titration curves AP Chemistry Understanding the shapes of acidbase titration curves AP Chemistry Neutralization Reactions go to Completion Every acidbase reaction produces another acid and another base. A neutralization reaction is

More information

Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. CP Chem Review 2 Matching Match each item with the correct statement below. a. activated complex d. activation energy b. reaction rate e. free energy c. inhibitor 1. the minimum energy colliding particles

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

Energy Diagram Endothermic Reaction Draw the energy diagram for exothermic and endothermic reactions. Label each part.

Energy Diagram Endothermic Reaction Draw the energy diagram for exothermic and endothermic reactions. Label each part. CP Chapter 18 Notes A Model for Reaction Rates Expressing Reaction Rates Average Rate = Δquantity Δtime The amount of increase or decrease depends on their mole ratios Units = or mol/ls Expressing Reaction

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

3Fe +2 (aq) + 2PO 4. NaHCO 3 + H 2 O. Chem 121 Quiz 3 Practice Fall 2017

3Fe +2 (aq) + 2PO 4. NaHCO 3 + H 2 O. Chem 121 Quiz 3 Practice Fall 2017 Chem 121 Quiz 3 Practice Fall 2017 The following quiz contains 22 questions (and bonuses!) valued at 1 point/question Name KEY G = H T S PV = nrt P 1 V 1 = P 2 V 2 P 1 /T 1 = P 2 /T 2 V 1 /T 1 = V 2 /T

More information

CHEMISTRY 12 EQUILIBRIUM PROPERTIES & ENTROPY AND ENTHALPY WORKSHEET CHEMISTRY 12 EQUILIBRIUM PROPERTIES WORKSHEET

CHEMISTRY 12 EQUILIBRIUM PROPERTIES & ENTROPY AND ENTHALPY WORKSHEET CHEMISTRY 12 EQUILIBRIUM PROPERTIES WORKSHEET CHEMISTRY 12 EQUILIBRIUM PROPERTIES & ENTROPY AND ENTHALPY WORKSHEET CHEMISTRY 12 EQUILIBRIUM PROPERTIES WORKSHEET 1) Write six statements that apply to all chemical equilibrium systems. (2 marks) System

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

Study Guide for Module 13 An Introduction to Equilibrium

Study Guide for Module 13 An Introduction to Equilibrium Chemistry 1020, Module 13 Name Study Guide for Module 13 An Introduction to Equilibrium Reading Assignment: Section 12.1 and Chapter 13 of Chemistry, 6th Edition by Zumdahl. Guide for Your Lecturer: 1.

More information

General Physical Science. Chemical and Physical Properties. Chemical and Physical Properties. Chapter 13 Chemical Reactions. Physical properties

General Physical Science. Chemical and Physical Properties. Chemical and Physical Properties. Chapter 13 Chemical Reactions. Physical properties General Physical Science Chapter 13 Chemical Reactions Chemical and Physical Properties Physical properties Observations about a substance changes that do not involve a change in the arrangement of the

More information

Chemical Equilibrium. Professor Bice Martincigh. Equilibrium

Chemical Equilibrium. Professor Bice Martincigh. Equilibrium Chemical Equilibrium by Professor Bice Martincigh Equilibrium involves reversible reactions Some reactions appear to go only in one direction are said to go to completion. indicated by All reactions are

More information

Equilibrium Practice Problems page 1

Equilibrium Practice Problems page 1 Equilibrium Practice Problems page 1 1988 D NH 4 HS(s) NH 3 (g) + H 2 S(g) ΔHº = +93 kilojoules The equilibrium above is established by placing solid NH 4 HS in an evacuated container at 25ºC. At equilibrium,

More information

Chemistry 201. Working with K. NC State University. Lecture 11

Chemistry 201. Working with K. NC State University. Lecture 11 Chemistry 201 Lecture 11 Working with K NC State University Working With K What is the relationship between pressure and concentration in K? How does one calculate K or components of K? How does one calculate

More information

CHEMICAL EQUATIONS WHAT BALANCING AN EQUATION MEANS

CHEMICAL EQUATIONS WHAT BALANCING AN EQUATION MEANS 17 CHEMICAL EQUATIONS WHAT BALANCING AN EQUATION MEANS WHAT IS A CHEMICAL EQUATION? A chemical equation is a way of representing a chemical reaction in symbolic form. For example, when hydrochloric acid

More information

Lecture 7: Chemical Equilbria--a bit more detail and some additional kinds of problems.

Lecture 7: Chemical Equilbria--a bit more detail and some additional kinds of problems. Lecture 7: Chemical Equilbria--a bit more detail and some additional kinds of problems. Lecture Overview: We get even more involved in the details by equilibria by relating G to K relating K c to K p comparing

More information

Name: Score: /100. Part I. Multiple choice. Write the letter of the correct answer for each problem. 3 points each

Name: Score: /100. Part I. Multiple choice. Write the letter of the correct answer for each problem. 3 points each Name: Score: /100 Part I. Multiple choice. Write the letter of the correct answer for each problem. 3 points each 1. Which of the following contains the greatest number of moles of O? A) 2.3 mol H 2 O

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

Chapter 9 Aqueous Solutions and Chemical Equilibria

Chapter 9 Aqueous Solutions and Chemical Equilibria Chapter 9 Aqueous Solutions and Chemical Equilibria At equilibrium, the rate of a forward process or reaction and that of the reverse process are equal. 9A The chemical composition of aqueous solutions

More information

b t u t sta t y con o s n ta t nt

b t u t sta t y con o s n ta t nt Reversible Reactions & Equilibrium Reversible Reactions Reactions are spontaneous if G G is negative. 2H 2 (g) + O 2 (g) 2H 2 O(g) + energy If G G is positive the reaction happens in the opposite direction.

More information

1.8 Thermodynamics. N Goalby chemrevise.org. Definitions of enthalpy changes

1.8 Thermodynamics. N Goalby chemrevise.org. Definitions of enthalpy changes 1.8 Thermodynamics 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 is formed from

More information

Experiment #14 Virtual Chemistry Laboratory (Chemical Equilibrium) Le-Chatelier s principle

Experiment #14 Virtual Chemistry Laboratory (Chemical Equilibrium) Le-Chatelier s principle Experiment #14 Virtual Chemistry Laboratory (Chemical Equilibrium) Le-Chatelier s principle I. PURPOSE OF THE EXPERIMENT (i) To understand the basic concepts of chemical equilibrium (ii) To determine the

More information

Unit 3: Solubility Equilibrium

Unit 3: Solubility Equilibrium Unit 3: Chem 11 Review Preparation for Chem 11 Review Preparation for It is expected that the student understands the concept of: 1. Strong electrolytes, 2. Weak electrolytes and 3. Nonelectrolytes. CHEM

More information

Part One: Solubility Equilibria. Insoluble and slightly soluble compounds are important in nature and commercially.

Part One: Solubility Equilibria. Insoluble and slightly soluble compounds are important in nature and commercially. CHAPTER 17: SOLUBILITY AND COMPLEX ION EQUILIBRIA Part One: Solubility Equilibria A. Ksp, the Solubility Product Constant. (Section 17.1) 1. Review the solubility rules. (Table 4.1) 2. Insoluble and slightly

More information

Equation Writing for a Neutralization Reaction

Equation Writing for a Neutralization Reaction Equation Writing for a Neutralization Reaction An Acid-Base reaction is also called a Neutralization reaction because the acid (generates H + or H 3 O + ) and base (generates OH ) properties of the reactants

More information

Solubility Equilibria

Solubility Equilibria Solubility Equilibria Heretofore, we have investigated gas pressure, solution, acidbase equilibriums. Another important equilibrium that is used in the chemistry lab is that of solubility equilibrium.

More information