Chapter 19, Problem 1TS

Assume the total number of molecules in a sample of liquid is about $\text{3}$ million trillion. One million trillion of these are molecules of some poison, while $2$ million trillion of these are water molecules. Show that the purity of this water is about $\text{67\%}$.

To determine

The purity of given water sample

Answer to Problem 1TS

Purity of liquid is fraction of water molecules in the total molecules present in the sample. So, the purity percentage is calculated by multiplying the fraction with $100$ shown as follows:

$\begin{array}{c}\text{Purity}=\frac{\text{Total number of water molecules in the liquid sample}}{\text{Total number of molecules in the liquid sample}}\times 100\text{ \%}\\ \text{=}\frac{2\text{ million trillion}}{\text{3 million trillion}}\times 100\text{ \%}\\ =67\text{ \%}\end{array}$

Explanation of Solution

In the given liquid sample, the total number of molecules in $\text{3}$ million trillion, out of which $1$ million trillion are poison and $2$ million trillion are water molecules. Purity of water sample is determined using the following formula:

$\begin{array}{c}\text{Purity}=\frac{\text{Total number of water molecules in the liquid sample}}{\text{Total number of molecules in the liquid sample}}\times 100\text{ \%}\\ \text{=}\frac{2\text{ million trillion}}{\text{3 million trillion}}\times 100\text{ \%}\\ =67\text{ \%}\end{array}$

Conclusion:

The purity of given liquid sample is $67\text{ \%}$.