A solution is prepared with a 1:2 dilution (1 part solute to 2 parts solvent). What fraction of the final solution is solute?

A solution is prepared with a 1:2 dilution (1 part solute to 2 parts solvent). What fraction of the final solution is solute?

• A. 1/2
• B. 1/3
• C. 2/3
• D. 3/4

Answer: (B)

In a dilution expressed as 1:2, there is 1 part solute and 2 parts solvent, giving a total of 3 equal parts in the final solution. The fraction that is solute is the solute part over the total parts: 1/3. So one third of the solution is solute. This would not fit if you thought the solute made up half of the mixture (that would require 1:1), two-thirds (which would mean 2 parts solute to 1 part solvent), or three-quarters (three parts solute to one part solvent).

In a dilution expressed as 1:2, there is 1 part solute and 2 parts solvent, giving a total of 3 equal parts in the final solution. The fraction that is solute is the solute part over the total parts: 1/3. So one third of the solution is solute.

This would not fit if you thought the solute made up half of the mixture (that would require 1:1), two-thirds (which would mean 2 parts solute to 1 part solvent), or three-quarters (three parts solute to one part solvent).