Name:
Stoichiometry Problems
Complete the following problems using dimensional analysis. Balance all equations. The answers are given in parenthesis at the end of each problem.
1. In the decomposition of aqueous sodium hydroxide, how many moles of sodium hydroxide are needed to produce 30.0 moles of liquid water? (60.0 moles NaOH)
___NaOH(aq) → ___Na2O(aq) + ___H2O(l)
2. In the single replacement reaction of solid lithium and aqueous magnesium nitrate, what mass of lithium combines with 75.0 grams of magnesium nitrate? (7.02 g Li)
___Li(s) + ___Mg(NO3)2(aq) → ___Mg(s) + ___ LiNO3(aq)
3. How many grams of lead (II) nitrate are needed to produce 60.0 grams of aqueous potassium nitrate in the double replacement reaction of aqueous potassium iodide and aqueous lead (II) nitrate? (98.3 g Pb(NO3)2)
___KI(aq) + ___Pb(NO3)2(aq) → ___PbI2(s) + ___KNO3(aq)
4. In the synthesis reaction of solid copper and solid sulfur, what mass of solid copper (I) sulfide is produced from 100.0 grams of sulfur? (496.4g Cu2S)
___Cu(s) + ___S8(s) → ___Cu2S(s)
5. In the single replacement reaction of solid magnesium and aqueous aluminum phosphate, if 7.00 moles of magnesium react, how many moles of aluminum phosphate would be needed? (4.67 mol AlPO4)
___Mg(s) + ___AlPO4(aq) → ___Al(s) + ___Mg3(PO4)2(aq)
6. When methane gas and oxygen gas react (in a complete combustion reaction) how many grams of gaseous water would be produced from 25.0 grams of methane? (56.1g water)
___CH4(g) + ___O2(g) → ___CO2(g) + ___H2O(g)
7. Solid lime (also known as calcium oxide) reacts with hydrochloric acid to form aqueous calcium chloride and liquid water. How many moles of HCl would be required to react with 7.5 moles of lime? How many moles of water would be formed? (15 mol HCl; 7.5 mol water)
___CaO(s) + ___HCl(aq) → ___CaCl2(aq) + ___H2O(l)
8. Solid zinc sulfide reacts with hydrochloric acid, what mass of zinc sulfide is needed to react with 10.54 grams of HCl? (14.09 g ZnS)
___ZnS(s) + ___HCl(aq) → ___ZnCl2(aq) + ___ H2S(g)
9. A 26.3 gram sample of solid potassium chlorate decomposed and produced 9.45 grams of oxygen gas. What is the percent yield for oxygen? (91.7%)
___KClO3(s) → ___KCl(s) + ___O2(g)
10. If 7.40 grams of aqueous calcium hydroxide react with nitric acid to produce 2.01 grams of liquid water, what is the percent yield? (55.8%)
___Ca(OH)2(aq) + ___HNO3(aq) → ___H2O(l) + ___Ca(NO3)2(aq)
11. A synthesis reaction of solid calcium and oxygen gas was completed in a lab and 234.9 grams of solid calcium oxide were produced from 75.00 grams of oxygen. What is the percent yield? (89.36%)
___Ca(s) + ___O2(g) → ___CaO(s)
Limiting Reactants, Percent Yield, and Empirical Formula Problems
For each of the following write balanced chemical equations (some have been given to you) and then solve the problem.
1. What is the maximum number of grams of PH3 that can be formed when 6.2g of solid phosphorus reacts with 6.0g of hydrogen gas to form PH3 gas?
___P4(s) + ___H2(g) → ___PH3(g)
2. Solid copper is formed when solid aluminum reacts with aqueous copper (II) sulfate in a single-replacement reaction. How many grams of copper can be obtained when 29.0g of Al react with 156g of copper (II) sulfate?
___Al(s) + ___CuSO4(aq) → ___Cu(s) + ___Al2(SO4)3(aq)
3. If you begin with 1250g of nitrogen gas and 225g of hydrogen gas in the reaction that forms ammonia gas (NH3), how much ammonia will be formed? What is the limiting reagent?
___N2(g) + ___H2(g) → ___NH3(g)
4. 550.g of aqueous lithium hydroxide reacts with 550.g of aqueous aluminum nitrate in a double replacement reaction. How many grams of solid aluminum hydroxide are produced? What is the limiting reactant?
___LiOH(aq) + ___Al(NO3)3(aq) → ___LiNO3(aq) + ___Al(OH)3(s)
5. Disulfur dichloride, S2Cl2, is used to vulcanize rubber. It is produced by treating molten sulfur with gaseous chlorine.
S8(l) + 4Cl2(g) → 4S2Cl2 (g)
If you begin with 32.0 g of sulfur and 71.0 g of Cl2how many grams of S2Cl2 can be produced? What is the limiting reactant?
6. Diborane, B2H6, can be prepared in the following reaction:
3 NaBH4 + 4BF3→ 3 NaBF4 + 2 B2H6
If you begin with 18.9 g of NaBH4 and excess BF3, and you isolate 7.50 g of B2H6 gas, what is the percent yield?
7. Red phosphorus reacts with bromine to produce PBr3.
2P(s) +3Br2(l) → 2PBr3(l)
If you use 12.7 g of bromine with excess phosphorus, what is the theoretical yield of PB3? If you isolate 10.9 g, what is the percent yield of this compound?
Stoichiometry Test Review
Review and be able to work all problems from your Stoichiometry Notes, Stoichiometry Worksheet, and Limiting and Excess Reactant Worksheet. Answers are given in ( ) at the end of each question.
Complete the following problem:
1. Sodium and water react. How many grams of sodium will react with water to produce 4.00 moles of hydrogen? (184 grams)
___ Na(s) + ___ H2O(l) → ___ NaOH(aq) + ___ H2(g)
2. How many moles of lithium chloride will be formed by the reaction of chlorine with 4.00 grams of lithium bromide? (0.0460 mol or 4.60X10-2 mol)
3. Aluminum will react with sulfuric acid. a. How many moles of H2SO4 will react with 18 mol of aluminum? b. How many moles of each product will form? (a. 27 mol; b. 27 mol hydrogen and 9.0 mol aluminum sulfate)
___ Al(s) + ___ H2SO4(aq) → ___ H2(g) + ___ Al2(SO4)3(aq)
4. What mass of acetylene, C2H2, will be produced from the reaction of 90. grams of calcium carbide with water in the following reaction? (37 grams)
___CaC2(s) + 2H2O(l) C2H2(g) + Ca(OH)2(s)
5. What mass of ZrCl4 can be produced if 862 grams of ZrSiO4 and 950. grams of chlorine are available to react according to the following equation? (1.10X103 grams)
ZrSiO4 + 2Cl2 ZrCl4 + SiO2 + O2
6. Heating zinc (II) sulfide in the presence of oxygen yields zinc (II) oxide and sulfur dioxide. If 1.72 moles of ZnS is heated in the presence of 3.04 moles of O2, which reactant will be used up? (ZnS is the limiting reactant)
7. Aluminum and oxygen react. If 3.17 grams of aluminum and 2.55 grams of oxygen are available, which reactant is limiting? (oxygen is limiting)
8. Bromine replaces iodine in magnesium iodide during a single replacement reaction. a. What mass of I2 is formed when 560 grams of MgI2 and 360 grams of Br2 react? (510 grams)
9. If 8.87 grams of As2O3 is used in the below reaction and 5.33 gram of arsenic is produced, what is the percent yield? (79.3%)
2As2O3 + 3C 3CO2 + 4As
10. Tungsten can be produced from its oxide by reacting the oxide with hydrogen at a high temperature according to the following equation. What is the percent yield if 56.9 grams of WO3 yields 41.4 grams of tungsten? (91.8%)
WO3 + 3H2 W + 3H2O