Review Exercises For Stoichiometry

Sample Exercises for Stoichiometry (Review for the 2nd Periodical Test 2009-10) Prepared by: Mr. Kim P. Bondoc Cebu Eastern College – High School Department Answer the following questions showing your step-wise solution. 1. Calculate the percent composition of each element in each of the following compounds: a. glucose b. sucrose c. methane d. carbon dioxide e. water 2. How many grams and molecules of glucose are in 45.00 moles? 3. How many moles and grams of ethyne are in 6.75 x 10 24 molecules? 4. How many moles and molecules of water are in 1.00 kilograms? 5. Determine the empirical and the molecular formula of a hydrocarbon that has a mass of 17.00 grams, if 6.00 grams of its sample can be decomposed into 4.50 grams carbon and 1.50 grams hydrogen. 5. A combustion analysis gives the following mass %: H= 9.15% C = 54.53% O = 36.32%. Determine the empirical and the molecular formula of the compound, given its molar mass to be 132.16 grams/mole. 6. A dry-cleaning solvent (molar mass = 146.99 g/mol) that contains C, H, and Cl is suspected to be a cancer-causing agent. When a 0.321 g sample was studied by combustion analysis, 0.576 g of CO2 and 0.0780 g of H2O formed. What is its empirical and molecular formula? 7. Assume that 85.00 grams of methane undergo combustion with 35.00 grams oxygen. How many grams of each, water and carbon dioxide are formed? What is the limiting and the excess reactant? 8. Follow-up question for #7. If 23.00 grams of carbon dioxide and 18.75 grams of water are actually formed from the combustion reaction, what is the percent yield carbon dioxide, and percent yield water? 9. Follow question for #7. How much (in grams) of the excess reactant is in surplus? *** God Bless! ***