Chapter 9 Chemical Reaction
Everyday Chemical Reaction O Can you name some? O Cooking Pizza O Changes the ingredients O Combustion O Driving to school burns gasoline O Wheelbarrow rusting (especially in the rain) O Iron coming in contact with oxygen O Respiration O Exhaling waste-co 2
Getting Rid of CO2
Chemistry of Respiration O CO 2 is a waste product of the krebs cycle. O To get rid of CO 2 it must be changed to H 2 CO 3. O H 2 CO 3 becomes H 2 O and CO 2 in the lungs.
9-1 Reactions and Equations O What is a reaction? O Examples O CO 2 + H 2 0 H 2 CO 3 O Fire turns a log into charcoal. O Heat turns an egg into a great sandwich!
9.1 Reactions and Equations O Evidence of a chemical reaction-
9.1 Reactions and Equations O Representing chemical rxn: O Equation are used to represent chemical rxn. O Reactants O Starting chemicals (on the left) O Products O New or formed chemical combinations (on the right) O Example: O Reactant 1 + reactant 2 Product 1 O Reactant 1 product 1 + product 2
9.1 Reactions and Equations O Symbols are use to denote certain aspects of an equation: O + adding two or more products or reactants O yields, creates O reaction is reversible O (s) solid state O (g) gaseous state O (l) liquid state O (aq) aqueous state, identifies acids/salt (cation and anion) in solution
9.1 Reactions and Equations O Equations- O Different ways to represent chemical equations: O Word equations O Hydrogen gas and oxygen gas yields water. O Formula (Skeleton) equations O H 2 + O 2 H 2 O O Chemical equations O 2H 2 (g) + O 2 (g) 2H 2 O (l)
Chemical Equations The significance of the chemical equation can be interpreted in several ways H 2 (g) + Cl 2 (g) 2HCl (aq) 1 molecule H 2 1 molecule Cl 2 2 molecules HCl 1 mol H 2 1 mol Cl 2 2 mol HCl 2 g H 2 71 g Cl 2 2 x 36.5 = 73 g HCl
SEPs O Word equation: O Solid Iron plus oxygen gas yields solid rust. O Formula equation:
SEPs O Word: O Liquid Water added to carbon dioxide gas makes solid glucose and oxygen gas. O Formula Equation:
Classifying Chemical Reactions I would classify them as classy
Chemical Reactions O There are 5 types of chemical reactions: O Synthesis O Decomposition O Single Replacement O Double Replacement O Combustion Mad Reaction!!!!!!
O1. Synthesis O Formula: OA + B AB O Examples: 2Mg (s) + O 2(g) 2MgO(s)
2. Combustion O Formula: O A + O 2 heat, light, or CO 2 and H 2 O O *** If C and H are the only reactants, CO 2 and H 2 O are the products O Examples: O C (s) + O 2 (g) CO 2 (g) O C 8 H 18 (l) + O 2 (g) CO 2 (g) + H 2 O (l)
SEPs Ethanol (C 2 H 6 O)(l) + Oxygen (g) Methane (g) + Oxygen (g) Hydrogen(g) + Oxygen (g)
O3. Decomposition O Formula: O AB A+B O Examples: Dead Deer deader deer 2H 2 O(l) electricity 2H 2 (g) + O 2 (g) 2H 2 CO 3 (aq) CO 2 (g) + H 2 O (l)
Replacement Rxn O Also called displacement rxns O Single Replacement and Double replacement. O Cations and Anions O More reactive metals will replace less reactive metals. O See list on the next slide O Use the list to predict whether or not a reaction will occur.
Most Reactive Metals Least Reactive Lithium Rubidium Potassium Calcium Sodium Magnesium Aluminum Manganese Zinc Iron Nickle Tin Lead Copper Silver Platinum Gold Halogens: Fluorine Chlorine Bromine Iodine
O4. Single Replacement O one element replaces a similar one in a compound A + BX AX + B O Element and Compound Compound and Element or Y + BX BY + X O Ex: Replacement of a Metal by another Metal. Al + Pb(NO 3 ) 2 Pb + Al(NO 3 ) 3
O5. Double Replacement O The ions of two compounds exchange in an aqueous solution to form two new compounds. AX + BY BX + AY SWITCHING PARTNERS O Ex: Formation of a Precipitate. Makes an insoluble substance fine, powdery solid. KI + Pb(NO 3 ) 2 PbI 2 + KNO 3 ****Double replacement reactions produce water, a precipitate, or a gas********
Easy steps to follow for a double replacement rxn. 1. Write the formula equations for the reactants. 2. Id the cations and anions in each compound. 3. Switch the anions to the other cations and write the products for the formulas. 1. Solid, Water, or Gas? 4. If yes, balance the equation. 5. Have someone check your work!!!!!!!!!
SEPs O Follow the steps: Aluminum Nitride + Lead sulfate AlN + PbSO 4 Lithium hydroxide + Iron(III) nitrate LiOH + Fe(NO 3 ) 3
SEPs O Sodium Hydroxide + Copper (II) Chloride O Mercury(II) carbonate + Tin (IV) Sulfide
Practice
Quiz Time Any Questions Before We Quiz?
Balancing Chemical Equations Law of the Conservation of Mass
Reactions and Equations O Balancing chemical equations- O Conservation of mass (ATOMS): O In ordinary chemical reactions the total mass of the reacting substances is equal to the total mass of the products formed. O Mass reactants = mass products O Number of reacting atoms = number of atoms produced
9.1 Reactions and Equations O Steps to balancing equations: 1. Write the correct formula for all reactants and products. 2. Total the numbers of each element for both sides of the equation. 3. Add coefficients to make the numbers balance (never change the subscripts). 4. If a polyatomic ion is found on both sides of the equation, always keep it together. 5. Check your work!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Ex: Write a balanced equation for the reaction between chlorine gas and aqueous sodium bromide to produce bromine gas and aqueous sodium chloride. Chlorine gas + sodium bromide bromine gas + sodium chloride Cl 2 + 2NaBr Br 2 + 2 NaCl Cl=2 Na=1 Br=1 Br=2 Na=1 Cl=1
Ex: Write a balanced equation for the reaction between aqueous aluminum sulfate and aqueous calcium chloride to produce soild aluminum chloride and a white solid of calcium sulfate. aluminum sulfate+ calcium chloride aluminum chloride +calcium sulfate Al 2 (SO 4 ) 3 + CaCl 2 AlCl 3 + CaSO 4
Page 287 #4 Problems
Tricks: If there is a single element, leave its balancing till last If the list isn t working because you have an odd number on one side and an even number on the other, try doubling it. Check after balancing that there is not a factor that could divide through all the coefficients to simplify the overall equation.
Practice Problems: 1. HgO Hg + O 2 2. BaCl 2 + NaOH NaCl + Ba(OH) 2 3. KBr + F 2 KF + Br 2 4. NaI + Pb(NO 3 ) 2 NaNO 3 + PbI 2 5. CaBr 2 + Na 3 P Ca 3 P 2 + NaBr
6. O 2 + N 2 N 2 O 4 7. H 2 SO 4 H 2 + S + O 2 8. NaI + Cs CsI + Na 9. H 2 + CO + O 2 H 2 CO 3 10. Ca + H 2 O Ca(OH) 2 + H 2
Practice
Quiz Time
9-3 Aqueous Solutions Lets Go Swimming
9-3 Aqueous Solutions O What are they: O Contains one or more substances call solutes dissolved in water. O Draw out what happens in solution O Single Replacement Rxn O Double Replacement Rxn
9-3 Aqueous Solutions O Covalent vs ionic compounds in water: O Covalent compounds stay together. O Ionic compounds come apart. O Explanation
Single Replacement Rxn O One metal/non-metal will replace another of the same in a solution. O A + BX AX + B O The metal/non-metal has to be more reactive than the one it is replacing. O Fe (s) + Pb(NO 3 ) 4 (aq) O Na (s) + K 2 CO 3 (aq) O CaCl 2 + I 2
Double Replacement O What are they: O Switching Partners: AX (aq) + BY (aq) BX (g, l, s) + AY (aq) Draw an Example
Reaction 2
Aqueous Solution O Double Replacement Reactions: O Will occur only if: O A precipitate forms O A gas forms O Or water O Otherwise the ions just stay in solution
9-3 Aqueous Solutions O Types of reactions in Aqueous Solutions: O Precipitates O Formation of water O Formation of gases
9-3 Aqueous Solutions O Formation of a precipitate: 2NaOH (aq) + CuCl 2 (aq) 2NaCl (aq) + Cu(OH) 2 (s) O All these exist as ions in solution: O Na+, OH- are together, and Cu 2+, Cl - are together O When both solution are mixed together, Cu 2+ and OH- over come the attraction of water and combine to form a solute. O Na + and Cl - are spectator ions.
9-3 Aqueous Solutions O Ionic equations: O Used to show ions in a solution are also ions written as ions in an equation. 2NaOH (aq) + CuCl 2 (aq) 2NaCl (aq) + Cu(OH) 2 (s) O Ionic Equation: 2Na + (aq) + 2OH - (aq) + Cu 2+ (aq) +2Cl- (aq) 2Na + (aq) + 2Cl - (aq) + Cu(OH) 2 (s)
9-3 Aqueous Solution O Complete ionic equation: O Shows all the particles in a solution as they exist. O Spectator Ions: O Ions that do not participate in the reaction. O Like Bailey at the 1986 Home coming. O Net ionic equation: O Ionic equation that include only the particles that participate in the reaction.
Net Ionic Equations O Will show only the ions that will produce either a gas, precipitate, or Water. O Solubility chart will show what cations and anions will produce a precipitate.
9-3 Aqueous Solutions O Ionic Equation: 2Na + (aq) + 2OH - (aq) + Cu 2+ (aq) +2Cl- (aq) 2Na + (aq) + 2Cl - (aq) + Cu(OH) 2 (s) O Net Ionic Equation 2OH - (aq) + Cu 2+ (aq) + Cu(OH) 2 (s)
9-3 Aqueous Solutions O How to write a net ionic equation: 1. Write the complete equation. 2. Determine if it will proceed forward 1. Is a soild, gas, or water formed 3. Balance it 4. Write the complete ionic equation. 5. Cross out all the spectator ions. 6. Finish off by writing only the ions that participate in the reaction.
SEPs O Determine if this reaction goes forward, and if it does, write the ionic equation, then the net ionic equation. O KI + AgNO 3 AgI + KNO 3
SEPs O Write the balanced equation, then the ionic equation, then the net ionic equation. O An aqueous solution of aluminum chloride and sodium hydroxide are mixed producing????????
9-3 Aqueous Solutions O Reactions that form water: HBr (aq) + NaOH (aq) Complete the reaction: HBr (aq) + NaOH (aq) H 2 O (l) + NaBr (aq)
SEPs O 2HCl (aq) + Ca(OH) 2 (aq) 2H 2 O + CaCl 2 (aq) O Then write then the ionic equation, then the net ionic equation.
9-3 Aqueous Solutions O Reactions that form gases: HI + Li 2 S O Results: 2HI(aq) + Li 2 S (aq) H 2 S (g) + 2LiI (aq) O Ionic equation: 2H + (aq) + 2I - (aq) + 2Li + (aq) + S 2- (aq) H 2 S (g) + 2Li + (aq) + 2I - (aq) O Net Ionic equation 2H + (aq) + S 2- (aq) H 2 S (g)
SEPs O Does this reaction occur, if so, write the net ionic equation: O H 2 SO 4 + KOH O BaCl 2 + I 2
9-3 Aqueous Solutions O Overall Equations: O A combination of hydrochloric acid and sodium carbonate, two reactions occur: O Double Replacement O Decomposition
Double Replacement- Decomposition HCl (aq) + NaHCO 3(aq) H 2 CO 3(aq) + NaCl (aq) H 2 CO 3 (aq) H 2 O (l) + CO 2 (g)
Getting Rid of CO2
SEPs