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Mole Review 1.) Calculate the number of moles in 60.4L of O 2. 2.) How many moles are there in 63.2g of Cl 2 ? 60.4L O 2 22.4L O 2 1 mol O 2 = 2.7 mol.

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Presentation on theme: "Mole Review 1.) Calculate the number of moles in 60.4L of O 2. 2.) How many moles are there in 63.2g of Cl 2 ? 60.4L O 2 22.4L O 2 1 mol O 2 = 2.7 mol."— Presentation transcript:

1 Mole Review 1.) Calculate the number of moles in 60.4L of O 2. 2.) How many moles are there in 63.2g of Cl 2 ? 60.4L O 2 22.4L O 2 1 mol O 2 = 2.7 mol O 2 63.2g Cl 2 70g Cl 2 1mol Cl 2 = 0.903mol Cl 2

2 Unit 08 Math In Chemistry Stoichiometry

3 Tiny Tyke Tricycle Company F + S + 3W + H + 2P → FSW 3 HP 2 Scheduled to make 640 tricycles. How many wheels should they order? Proportional Relationships

4 I have 5 eggs. How many cookies can I make? 3/4 c. brown sugar 1 tsp vanilla extract 2 eggs 2 c. chocolate chips Makes 5 dozen cookies. 2 1/4 c. flour 1 tsp. baking soda 1 tsp. salt 1 c. butter 3/4 c. sugar 5 eggs5 doz. 2 eggs = 12.5 dozen cookies Ratio of eggs to cookies

5 Proportional Relationships Stoichiometry Stoichiometry – mass relationships between substances in a chemical reaction for example: you can determine the amount of a compound required to make another compound – based on the mole ratio Mole Ratio Mole Ratio – indicated by coefficients in a balanced equation 2 Mg + O 2  2 MgO 2 Moles of magnesium react with 1 mole of oxygen to form 2 moles of magnesium oxide.

6 2 Mg + O 2  2 MgO What would be the mole ratio of magnesium to magnesium oxide? 2 : 2 Conversion factor = 2 mol Mg 2 mol MgO What would be the mole ratio of oxygen to magnesium? 1 : 2 Conversion factor = 1 mol O 2 (Mole Ratio) 2 mol Mg

7 Practice 5 F 2 + 2NH 3  N 2 F 4 + 6HF 1. What is the mole ratio of NH 3 to F 2 ? Write the mole ratio as a conversion factor. 2. What is the mole ratio of HF to N 2 F 4 ? Write the mole ratio as a conversion factor. 2:5 2mol NH 3 5mol F 2 6:1 6mol HF 1mol N 2 F 4

8 Stoichiometry Steps 1. Identify known & unknown. 2. Convert known to mole. (if necessary) 3. Use Mole Ratio. 4. Convert moles to unknown unit. (if necessary) known Mol of known Mol of unknown Mole ratio- get from equation Mol of unknown Units of unknown

9 Mass-Mass Stoichiometry Mass of reactants equals the products Law of Conservation of Mass ONLY mass and atoms are conserved in every chemical reaction Known g 1 mol Known Molar mass Known mol unknown mol known Mol ratio- get from equation Molar mass unknown 1 mol unknown

10 Mass-Mass Stoichiometry #1 The reaction of fluorine with ammonia produces dinitrogen tetrafluoride and hydrogen fluoride. 5F 2 + 2 NH 3 → N 2 F 4 + 6HF How many grams of NH 3 are required to produce 7.38g HF?

11 Mass-Mass Stoichiometry #2 5F 2 + 2 NH 3 → N 2 F 4 + 6HF How many grams of N 2 F 4 can be produced from 265g F 2 ?

12 Mass-Mass Stoichiometry #3 2C 2 H 2 + 5O 2 → 4CO 2 + 2H 2 O How many grams of oxygen are required to burn 52.0g C 2 H 2 ?

13 C. Stoichiometry Problems How many grams of silver will be formed from 12.0 g copper? 12.0 g Cu 1 mol Cu 63.55 g Cu = 40.7 g Ag Cu + 2AgNO 3  2Ag + Cu(NO 3 ) 2 2 mol Ag 1 mol Cu 107.87 g Ag 1 mol Ag 12.0 g? g

14 Calculate the number of grams of NH 3 produced by the reaction of 5.40 g of hydrogen with an excess of nitrogen. N 2 + 3H 2 → 2NH 3 C. Stoichiometry Problems

15 Acetylen gas (C 2 H 2 ) is produced by adding water to calcium carbide (CaC 2 ). CaC 2 + 2H 2 O  C 2 H 2 + Ca(OH) 2 How many grams of acetylene are produced by adding water to 5.00 g CaC 2 ? Using the same equation, determine how many moles of CaC 2 are needed to react completely with 49.0 g H 2 O.

16 __S + __O 2 → __SO 3  Write the equation.  Balance the equation.  How many moles of SO 3 are produced when there are 4.5 moles of S ?  Known =  Unknown = Mole-Mole Examples #1

17 2C 3 H 7 OH + 9O 2 → 6CO 2 + 8H 2 O  Write the equation.  Calculate the moles of oxygen needed to react with 3.40 moles of isopropyl alcohol. Mole-Mole Examples #2 Isopropyl alcohol (C 3 H 7 OH) burns in the air to this equation:

18 2C 3 H 7 OH + 9O 2 → 6CO 2 + 8H 2 O  Find the moles of water when 6.20 mol O 2 reacts with C 3 H 7 OH. Mole-Mole Examples #3

19 C. Stoichiometry Problems How many moles of KClO 3 must decompose in order to produce 9 moles of oxygen gas? 9 mol O 2 2 mol KClO 3 3 mol O 2 = 6 mol KClO 3 2KClO 3  2KCl + 3O 2 ? mol9 mol

20 Volume-Volume Stoichiometry Formula to use: Known (L) 1 mol known mol unknown 22.44 L unknown 1 22.4 L known mol known 1 mol unknown

21 C 3 H 8 + 5O 2 → 3CO 2 + 4H 2 O If 20 liters of oxygen are consumed in the above reaction, how many liters of carbon dioxide are produced? Volume Example #4

22 C. Mixed Stoichiometry Problems How many moles of KClO 3 must decompose in order to produce 9 moles of oxygen gas? 9 mol O 2 2 mol KClO 3 3 mol O 2 = 6 mol KClO 3 2KClO 3  2KCl + 3O 2 ? mol9 mol

23 How many grams of KClO 3 are required to produce 9.00 L of O 2 at STP? 9.00 L O 2 1 mol O 2 22.4 L O 2 = 32.8 g KClO 3 2 mol KClO 3 3 mol O 2 122.55 g KClO 3 1 mol KClO 3 ? g9.00 L C. Mixed Stoichiometry Problems 2KClO 3  2KCl + 3O 2

24 Limiting Reactants/Reagents Available Ingredients Available Ingredients – 4 slices of bread – 1 jar of peanut butter – 1/2 jar of jelly Limiting Reactant/Reagents Limiting Reactant/Reagents bread Excess Reactants/Reagents Excess Reactants/Reagents peanut butter and jelly

25 Limiting Reactants/Reagents Limiting Reactant/Reagent Limiting Reactant/Reagent – used up in a reaction – determines the amount of product Excess Reactant/Reagent Excess Reactant/Reagent – added to ensure that the other reactant is completely used up – cheaper & easier to recycle

26 Limiting Reagents 1. Write a balanced equation. 2. For each reactant, calculate the amount of product formed. 3. Smaller answer indicates: – limiting reactant – amount of product

27 Limiting Reagents 79.1 g of zinc react with 0.90 L of HCl. Identify the limiting and excess reactants. How many liters of hydrogen are formed at STP? Zn + 2HCl  ZnCl 2 + H 2 79.1 g ? L 0.90 L

28 Limiting Reagents 79.1 g Zn 1 mol Zn 65 g Zn = 27.3 L H 2 1 mol H 2 1 mol Zn 22.4 L H 2 1 mol H 2 Zn + 2HCl  ZnCl 2 + H 2 79.1 g ? L 0.90 L

29 Limiting Reagents 0.90 L HCl 1 mol HCl 22.4 L HCl = 0.45 L H 2 1 mol H 2 2 mol HCL 22.4 L H 2 1 mol H 2 Zn + 2HCl  ZnCl 2 + H 2 79.1 g ? L 0.90 L

30 Limiting Reagents Zn: 27.3 L H 2 HCl: 0.45 L H 2 Limiting reagent: HCl Excess reagent: Zn

31 Percent Yield Percent yield- the ratio of the actual yield to the theoretical yield Actual yield- the amount of product formed when a reaction is carried out in the laboratory Theoretical yield- the calculated amount of product formed during a reaction

32 Percent Yield calculated on paper measured in lab

33 Percent Yield When 45.8 g of K 2 CO 3 react with excess HCl, 46.3 g of KCl are formed. Calculate the theoretical and % yields of KCl. K 2 CO 3 + 2HCl  2KCl + H 2 O + CO 2 45.8 g? g actual: 46.3 g

34 Mole - Mole Knownmol of unknown mol of known Mol Ratio – from equation Mass - Mass Known g molar mass known 1 mol known mol of unknown mol of known1 mol unknown molar mass unknown Known L 22.4 L known 1 mol known mol of unknown mol of known1 mol unknown 22.4 L unknown particles 6.02 × 10 23 particles OR Other Formulas to Use

35 Stoichiometry Problems How many moles of KClO 3 must decompose in order to produce 9 moles of oxygen gas? 9 mol O 2 2 mol KClO 3 3 mol O 2 = 6 mol KClO 3 2KClO 3  2KCl + 3O 2 ? mol9 mol

36 Stoichiometry Problems How many grams of KClO 3 are req’d to produce 9.00 L of O 2 at STP? 9.00 L O 2 1 mol O 2 22.4 L O 2 = 32.8 g KClO 3 2 mol KClO 3 3 mol O 2 122.55 g KClO 3 1 mol KClO 3 ? g9.00 L 2KClO 3  2KCl + 3O 2

37 Stoichiometry Problems How many grams of silver will be formed from 12.0 g copper? 12.0 g Cu 1 mol Cu 63.55 g Cu = 40.7 g Ag Cu + 2AgNO 3  2Ag + Cu(NO 3 ) 2 2 mol Ag 1 mol Cu 107.87 g Ag 1 mol Ag 12.0 g? g

38 63.55 g Cu 1 mol Cu Stoichiometry Problems How many grams of Cu are required to react with 1.5 L of 0.10M AgNO 3 ? 1.5 L.10 mol AgNO 3 1 L = 4.8 g Cu Cu + 2AgNO 3  2Ag + Cu(NO 3 ) 2 1 mol Cu 2 mol AgNO 3 ? g 1.5L 0.10M


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