Question

What volume of a 0.20 M NaOH solution would a student need to make 500 mL of a 0.10 M NaOH solution?

25 mL

100 mL

200 mL

250 mL


The phrase “like dissolves like” refers to the fact that *


A Polar solvents dissolve no polar solutes and vice versa


B Solvents can only dissolve solutes of similar molar mass


C Gases can only dissolve other gases


D Polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes

Answer 1

For the dilution, the following relation operates:

$c_1V_1 = c_2V_2$ ,

where $c$ is the concentration and $V$ is the volume of the solution before (1) and after (2) the dilution. This means that the number of the moles of the solute is constant. Therefore, to make 500 mL ($V_2$) of a 0.10 M ($c_2$ ) NaOH solution from 0.20 M ($c_1$) NaOH solution, the student needs $c_2·V_2/c_1 = 0.10·500/0.20 = 250$ mL of 0.20 M solution.

The phrase "like dissolves like" refers to the fact that polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes.

Answer: 250 mL of 0.20 M solution is needed to make 500 mL of a 0.10 M NaOH solution. The phrase "like dissolves like" refers to the fact that polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes.