Chapter 16, Problem 1STP

Interpretation Introduction

Interpretation: The milliliters of water present in $95\text{mL}$ of an aqueous solution of rubbing alcohol is to be calculated in which the volume percentage of rubbing alcohol is $65\%$ .

Concept introduction: The concentration of solute in an aqueous solution is expressed by using the term volume percentage. Volume percentage is the ratio of the volume of a salute to the total volume of the solution and then multiplied by a hundred to make the value in percentage.

The formula used for the determination of concentration or volume percentage is,

  $\text{Percentage}\text{volume}=\frac{\text{Volume}\text{of}\text{solute}}{\text{Total}\text{volume}\text{of}\text{solution}}$

Answer to Problem 1STP

Correct option: The correct option to this question is (C).

Explanation of Solution

The percentage of water present in the aqueous solution of rubbing alcohol that has $65\%$ rubbing alcohol can be calculated by subtracting the volume percentage of rubbing alcohol by a hundred. Since the total volume percentage is $100$ .

Therefore,

  $\begin{array}{c}\text{The}\text{volume}\text{percentage}\text{of}\text{water}=100-65\\ =35\%\end{array}$

Upon multiplying the volume percentage of water with the total volume of solution, $95\text{mL}$ the volume of water present in the solution will be obtained in milliliters.

That is,

  $\begin{array}{c}\text{The}\text{volume}\text{of}\text{water}=95\text{mL}\times 35\%\\ =95\times 0.35\\ =33.25\text{mL}\\ \approx \text{33}\text{mL}\end{array}$