Sample Questions - Chemical Calculations

FIRST YEAR CHEMISTRY

Assessment Test

Sample Questions, Chemical Calculations

1. Find the mass percentage of iron in Fe ₂ O ₃ . Atomic weights: Fe 55.8, O 16.0.

2. What is the molar mass of SrCl₂ . 6H₂O? Include the correct units in your answer. Atomic weights: Sr 87.6, Cl 35.5, H 1.01, O 16.0.

3. How many moles of oxygen are required to react with 12.0 grams of carbon to produce carbon monoxide? Atomic weights: C 12.0, O 16.0. The balanced equation is

2 C + O₂   --> 2 CO

4. How many moles of NaOH are required to react with the SO₂   produced by the oxidation of 0.500 moles of FeS₂? The balanced equations are

4 FeS₂   + 11 O₂   --> 2 Fe₂O₃   + 8 SO₂

SO₂   + 2 NaOH --> Na₂SO₃   + H₂O

5. A compound of sulfur and fluorine contains 29.7% S and 70.3% F (percentages are by mass). What is the empirical formula of the compound?

6. (a) How many grams of AlCl₃   can be produced when 0.100 moles of aluminum reacts with excess chlorine? Atomic weights: Al 27.0, Cl 35.5. The balanced equation is

2 Al + 3 Cl₂   --> 2 AlCl₃ (b) What is the % yield of this reaction if 12.5 grams of AlCl₃   are actually obtained? 7. What is the molarity of a copper(II) chloride solution if 10.0 grams of CuCl ₂   are dissolved in water to give 250.0 mL of solution? The molar mass of CuCl ₂   is 134.5 g/mol.

8. What is the molarity of a sodium hydroxide solution if 50.0 mL of the solution requires 38.6 mL of 0.0976 M HCl for titration?  

Answers

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Last revised: Aug. 16th, 2006 by A. van der Est

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