Volume/Volume Percent Solution Problems

Use ratio and proportion to determine the amount of hydrate needed.

111.1 g/mol anhydrous

0.200 g anhydrous

---------------------- = ------------------

147.1 g/mol hydrate

x g hydrate

(147.1 g/mol hydrate) (0.200 g anhydrous)

x g hydrate = --------------------------------------

111.1 g/mol anhydrous

x g hydrate = 0.265 g

2-30. VOLUME/VOLUME PERCENT SOLUTION PROBLEMS

When a solution has a liquid solute in a liquid solvent, percent concentration is

expressed as volume per unit volume (v/v). When a number expressing a liquid solute

in a liquid solvent is followed by a percent symbol (%) then the concentration is a v/v

concentration.

a. Problem Solving. Methods developed earlier for solving weight per volume

solutions may be applied to volume per volume solutions.

b. Example 1. How much alcohol is required to make 100 mL of a 20.0 mL/dL

alcohol solution?

Solution. Read the problem carefully and determine the unknown quantity.

Milliters of alcohol.

Express the volume in deciliters.

1 dL

100 mL X -------- = 1.00 dL

100 mL

Multiply the volume expressed in deciliters times the percent concentration to

determine the volume of solute needed to prepare the solution.

20.0 mL

1.00 dL X -------- = 20.0 mL

MD0837

2-15