Question

A 5.098 mass % aqueous solution of potassium hydroxide has a density of 1.05 g/mL. Calculate the molality of the solution. Give your answer to 3 decimal places.

Answer 1

Answer: The molarity of solution is 0.954 M

Explanation:

We are given:

5.098 mass % solution of potassium hydroxide

This means that 5.098 grams of potassium hydroxide is present in 100 grams of solution

To calculate volume of a substance, we use the equation:

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

Density of solution = 1.05 g/mL

Mass of solution = 100 g

Putting values in above equation, we get:

$1.05g/mL=\frac{100g}{\text{Volume of solution}}\\\\\text{Volume of solution}=\frac{100g}{1.05g/mL}=95.24mL$

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

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

Given mass of potassium hydroxide = 5.098 g

Molar mass of potassium hydroxide = 56.1 g/mol

Volume of solution = 95.24 mL

Putting values in above equation, we get:

$\text{Molarity of solution}=\frac{5.098\times 1000}{56.1\times 95.24}\\\\\text{Molarity of solution}=0.954M$

Hence, the molarity of solution is 0.954 M