Question

A throat spray is 1.40% by mass Phenol, C6H5OH in water. If the solution has a density of 0.9956 g/ml, calculate the molarity of the solution.

Answer 1

Answer: The molarity of solution is 1.08 M

Explanation:

We are given:

(m/m) of phenol = 1.40 %

This means that 1.40 g of phenol is present in 100 g of solution.

To calculate volume of solution, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of solution = 0.9956 g/mL

Mass of solution = 100 g

Putting values in above equation, we get:

$0.9956g/mL=\frac{100g}{\text{Volume of solution}}\\\\\text{Volume of solution}=100.442mL$

To calculate the molarity of solution, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$

We are given:

Mass of solute (phenol) = 1.40 g

Molar mass of phenol = 94.11 g/mol

Volume of solution = 100.442 mL

Putting values in above equation, we get:

$\text{Molarity of solution}=\frac{1.40g\times 1000}{94.11g/mol\times 100.442mL}\\\\\text{Molarity of solution}=0.15M$

Hence, the molarity of solution is 0.15 M