Oxidation and Molarity
Supplemental Instruction
Iowa State University / Leader: / Kia
Course: / CHEM 177
Instructor: / Anand
Date: / February 14th, 2017

Concept Check

1.  What is the unit of Molarity? How do you find Molarity?

2.  What does the activity series tell you?

3.  What are the three substances that typically result in a gas-forming reaction?

Practice Problems

4.  Redox review – give the oxidation number of the indicated ions

  1. O in O2
  1. Na in NaCl
  1. Mn in MnO2
  1. Cl in Fe(ClO2)3
  1. Fe in Fe(ClO2)3
  1. I in Mg(IO3)2

5.  In the following redox reactions, label which element is oxidized and which is reduced.

a.  N2(g) +3 H2(g) à 2 NH3(g)

b.  3 Fe(NO3)2(aq) + 2 Al(s) à 3 Fe(s) +2 Al(NO3)3(aq)

c.  Cl2(aq) + 2 NaI(aq) à I2(aq) + 2 NaCl(aq)

6.  Using the activity series, write a balanced chemical equation for the following reactions (if no reaction occurs write NR)

  1. Nickel metal is added to a solution of copper (II) nitrate
  1. A solution of zinc nitrate is added to a solution of magnesium sulfate
  1. Hydrochloric acid is added to gold metal

7.  Molarity manipulation practice

  1. Calculate the molarity of a solution made by dissolving 12.5 grams of Na2CrO4 in enough water to form exactly 750 mL of solution
  1. How many moles of KBr are present in 150 mL of a 0.112 M solution?
  1. How many milliliters of 6.1 M HCl solution are needed to obtain 0.150 mol of HCl?

Challenge/review questions

8.  Pure acetic acid, known as glacial acetic acid, is a liquid with a density of 1.049 g/mL at 25 dC. Calculate the molarity of a solution of acetic acid made by dissolving 20.00 mL of glacial acetic acid at 25 dC in enough water to make 250.0 mL of solution.

9.  A sample of 7.75 g of Mg(OH)2 is added to 25.0 mL of 0.200 M HNO3

  1. Write the chemical equation for the reaction that occurs.
  1. Which is the limiting reactant in the reaction?
  1. How many moles of Mg(OH)2, HNO3, and Mg(NO3)2 are present after the reaction is complete?