Answers

1. Calculate the molarity of a solution prepared by dissolving 11.5 g of solid NaOH in enough water to make

1.50 L of solution.

Answer=0.192 M NaOH

2. Calculate the molarity of a solution prepared by dissolving 1.56 g of gaseous HCl into enough water to

make 26.8 mL of solution.

Answer=1.59 M HCl

3. Calculate the molarity of a solution prepared by dissolving 1.00g of ethanol, C2H5OH, in enough water to

give a final volume of 101 mL.

Answer= 0.215 M

4. Give the concentrations of all the ions in each of the following solutions:

a) 0.50 M Co(NO₃)₂ Answer= 0.50 M Co²⁺ and 1.0 M NO₃^-

b) 1 M FeCl3 _{Answer = 1M Fe}³⁺ _{and 3M Cl}^-

5. Give the concentrations of the ions in each of the following solutions:

a) 0.10 M Na₂CO₃ Answer= 0.20 M Na⁺ and CO₃^2- 0.10 M

b) 0.010 M Al₂(SO₄)₃ Answer= 0.020 M Al⁺³ and 0.030M SO₄^2-

6. How many moles of Ag⁺ ions are present in 25 mL of a 0.75 M AgNO₃ solution?

Answer= 1.9 x 10^-2 mol Ag⁺

7. Calculate the number of moles of Cl^- ions in 1.75 L of 1.0 x 10^-3 M AlCl₃

_Answer= 5.3 x 10^-3 mol Cl^-

8. To analyze the alcohol content of a certain wine, a chemist needs 1.00 L of an aqueous 0.200 M K₂Cr₂O₇ solution. How much solid K₂Cr₂O₇ (molar mass = 294.2 g) must be weighed out to make

this solution?

Answer=58.8 g K₂Cr₂O₇

9. Formalin is an aqueous solution of formaldehyde, HCHO, used as a preservative for biological specimens.

How many grams of formaldehyde must be used to prepare 2.5 L of 12.3 M formalin?

Answer= 930 g HCHO