2011 2012 pretest for percent yield, empirical and molecular formulas
1. 2011-2012 Empirical Formula, Molecular Formula and Percent Yield Pretest
1a. Write the equation for the reaction of iron (III) phosphate with sodium sulfate to make iron (III) sulfate and sodium
phosphate.
1b. If I perform this reaction with 25 grams of iron (III) phosphate and an excess of sodium sulfate, how many grams of iron (III)
sulfate can I make?
1c. If 18.5 grams of iron (III) sulfate are actually made when I do this reaction, what is my percent yield?
1d. Is the answer from problem #3 reasonable? Explain.
2. What is the empirical formula for P4H10 ?
3. A compound has an empirical formula of C3H5O2 and a molar mass of 146.14 grams. What is the molecular formula of this
compound?
4. Calculate the molecular formula of a compound that is 21.10% N, 6.06% H, 24.30% S and 48.45% O if the molar
mass is 396 g/mol.
5. Calculate the empirical formula of a compound that is 37.70% Na, 22.95, Si, and 39.34% O.
