Chapter 12- Stoichiometry Stoichiometry- using chemical formulas to determine molar and mass relationships from balanced chemical equations

The Mole Ratio PRACTICE

Mole Ratio Practice Write all the possible mole relationships that can be written from the following equation.

Mole:Mole __CO 2 (g) + __LiOH(s)  __Li 2 CO 3 (s) + __H 2 O(l) 1.How many moles of lithium hydroxide are required to react with 20 moles of CO 2 ? (answer: 40 moles lithium hydroxide) 2.If 1.25 moles of water are produced, how many moles of carbon dioxide were used? 3.You have 3.55 moles of CO 2, how moles of lithium carbonate can you make?

Mole:Mass CO 2 (g) + H 2 O(l)  C 6 H 12 O 6 (s) + O 2 (g) 1.What mass of CO 2, in grams, is needed to react with 3.00 moles of H 2 O during photosynthesis? (Answer: 132 g) 2.How many grams of glucose can be made from those 3.00 moles of water? 3.It is measured that grams of oxygen are produced, how many moles of carbon dioxide must have been used?

Mass:Mass: Sn(s) + HF(g)  SnF 2 (s) + H 2 (g) 1.How many grams of SnF 2 can be produced from 30.0 g of tin? (answer: 39.6 g) 2.If 2.54g of hydrogen are produced, how many grams of tin were used? 3.If you have g of tin available, what is the maximum amount of SnF 2 you can make?

Practice (try these tonight) 1.Sulfuric acid reacts with sodium hydroxide in a double replacement reaction. If you start with 5.25 moles of NaOH, how many moles of water can you make? 2.If you start with grams of NaOH, how many moles of sodium sulfate can you make? 3.If you start with 55.1 grams of NaOH, how many grams of sodium sulfate can you produce?

Limiting Reactants Ingredients 2 1/4 cups all-purpose flour 1 teaspoon baking soda 1 teaspoon salt 1 cup (2 sticks) butter, softened 3/4 cup granulated sugar 3/4 cup packed brown sugar 1 teaspoon vanilla extract 2 large eggs 2 cups (12-oz. pkg.) 1 cup chopped nuts Yield: 24 cookies How many cookies can be made if I only have 1 stick of butter and 1 cup of sugar (and the exact quantity of the other ingredients in the recipe)?

Limiting Reactants (5 steps) Strategy #1 1.Write and/or balance the equation ___Mg3N2 + ___H2O ___Mg(OH)2 + __NH3 2.Determine the mole ratio of the reactants in the equation 3.Determine the mole ratio of the reactants from the given quantities in the problem (Hint: Convert grams to moles) 4.Compare the mole ratios to determine which reactant is limiting. 5. Using the limiting reactant, determine the amount of product that can be produced using stoichiometry.

Limiting Reactants (3 steps) Strategy #2 ___KBr(aq) + ___Cl 2 (aq)  ___KCl(aq) + ___Br 2 (l) Write and/or balance the equation. Using Stoichiometry, solve for the amount of product that can be produced from one of the reactants. Using Stoichiometry, solve for the amount of product that can be produced from the other reactant. Whichever reactant yields the least amount of product is the limiting reactant.

Handling Excess Reactant If one reactant is limiting, then the other is in excess To determine how much of the excess reactant remains after the reaction is complete, You need to determine how much of it is actually needed through stoichiometry using the limiting reactant as a starting point. Then, subtract this quantity from the amount given in the equation.

Percent Yield ( How good of a scientist are you…..Maybe?) ___Al(OH) 3 (s) + ___HCl (aq) g ___AlCl 3 (aq) + ___ H 2 O (l) 1. If you start with 50.3 g of Al(OH)3 and an excel of HCl and you isolate 39.5 g of AlCl3, what is the percent yield? (amount produced in the lab) (amount determined through stoichiometry)