Chapter 14, Problem 20E

Interpretation Introduction

Interpretation:

The solution is 75% ${\text{H}}_{\text{2}}{\text{PO}}_{\text{4}}$ by mass. The density of solution is 1.57 g/mL. The molarity of ${\text{H}}_{\text{2}}{\text{PO}}_{\text{4}}$ in the solution needs to be determined.

Concept introduction:

Mass percent of any species in the solution can be calculated from its mass and mass of the solution. For example, if mass of the species is x and that of solution is y, the mass percent of the solution can be calculated as follows:

$\%m=\frac{x\text{ g}}{y\text{ g}}\times 100\%$

The molarity of solution is defined as number of moles of solute in 1 L of the solution.

$M=\frac{n}{V\left(\text{L}\right)}$

The density of the solution is related to mass and volume of solution as follows:

$d=\frac{m_{\text{solution}}}{V_{\text{solution}}}$

The number of moles of substance can be calculated from mass and molar mass as follows:

$n=\frac{m}{M}$

Here, m is mass and M is molar mass.