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Chapter 12 Chemical Quantities . 12.2 Using Moles. Warm-up: Making a Sandwich. How Many Sandwiches?. What is Stoichiometry?. Stoichiometry is the study of quantitative relationships between amounts of reactants used and products formed by a chemical reaction.
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Chapter 12 Chemical Quantities 12.2 Using Moles
Warm-up: Making a Sandwich How Many Sandwiches?
What is Stoichiometry? Stoichiometry is the study of quantitative relationships between amounts of reactants used and products formed by a chemical reaction. A balanced chemical equation is needed to solve any stoichiometry problem
Practical Applications of Stoichiometry In a spacecraft, the carbon dioxide exhaled by astronauts can be removed by its reaction with lithium hydroxide, LiOH, according to the following chemical equation. CO2(g) + 2LiOH(s) Li2CO3(s) + H2O(l) How many moles of lithium hydroxide are required to react with 20 mol of CO2, the average amount exhaled by a person each day?
Strategy – Relate everything to the mole The mole is the common thread that links reactants to products. 1CO2(g) + 2LiOH(s) 1Li2CO3(s) + 1H2O(l) Mole Ratios
Practice Problems – Mole to Mole How many moles of oxygen are needed to fully combust 1.6 moles of ethane(C2H6)? Balanced Chemical Equation How many moles of water are formed when 3.8 moles of Hydrogen react with an excess of Oxygen? O
Warm-up Felix has six of the same Charazard cards. For every 3 Charazard cards that he trades in, he can get one Arcaninecard. Each Arcanine card is valued at $2.50. How much money can Felix make from a trade if he trades in all of his Charazard cards? 3 1
Practice Problems – Mole to Mass How many moles of oxygen are needed to produce 15.6g of carbon dioxide? How many grams of water are formed when 4.5 moles of oxygen react with an excess of hydrogen? O
Practice Problems – Mass to Mass How many grams of ethane are needed to produce 23.4g of water? How many grams of water are formed when 18.6 grams of oxygen react with an excess of hydrogen? O
Warm-up At STP, which of the following would have the greatest volume? 1mole = NO 1mole = He 1mole = CH4
Practice Problems – Volume at STP How many liters of oxygen are required to react with 5.6 liters of hydrogen to produce water at STP? O
Warm-up • You mix together the ingredients to make a batch of chocolate chip cookies. The recipe says that the yield should be 3 dozen cookies. You only get 30 cookies. What percentage of the expected yield did you get?
Percent Yield Stoichiometric calculations provide a theoretical yield or maximum amount of product that can be produced from a given amount of reactants. The actual yield is the amount that is actually produced when a reaction is carried out. The percent yield reflects the ratio of the theoretical and actual yields
Practice Problem - Percent Yield When 4.3 grams of sodium are combined with aluminum nitrate in the following equation, 1.52g of aluminum are produced. What is the percent yield of aluminum?