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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. - PowerPoint PPT Presentation
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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 StoichiometryIn 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
molLiOHmolCO21 2
32
2
11
COmolLimolCO
OmolHmolCO
2
2
11
3212
COmolLimolLiOH
OmolHmolLiOH
212
How many moles of oxygen are needed to fully combust 1.6 moles of ethane(C2H6)?
OHCOOHC 22262 ________
Practice Problems – Mole to Mole
How many moles of water are formed when 3.8 moles of Hydrogen react with an excess of Oxygen?
O
Balanced Chemical Equation
Warm-upFelix has six of the same Charazard cards. For every 3 Charazard cards that he trades in, he can get one Arcanine card. 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
How many moles of oxygen are needed to produce 15.6g of carbon dioxide?
OHCOOHC 22262 6472
Practice Problems – Mole to Mass
How many grams of water are formed when 4.5 moles of oxygen react with an excess of hydrogen? O
How many grams of ethane are needed to produce 23.4g of water?OHCOOHC 22262 6472
Practice Problems – Mass to Mass
How many grams of water are formed when 18.6 grams of oxygen react with an excess of hydrogen?
O
Warm-upAt STP, which of the following would have the greatest volume?
1mole = He
1mole = NO 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 YieldStoichiometric 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 100
)()( xtryStoichiomelYieldTheoretica
ExperimentdActualYielldPercentYie
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?3𝑁𝑎+𝐴𝑙 ¿
