Concentrated phosphoric acid is sold as a solution of 85% phosphoric acid and 15% water by mass. Given that its molarity is 15 M, calculate the density of concentrated phosphoric acid.

The density of phosphoric acid is 1.98 g/mL

Explanation:

We are given:

85% phosphoric acid and 15 % water

This means that 85 grams of phosphoric acid and 15 grams of water are present in 100 grams of solution

To calculate the volume of water, we use the equation:

      ......(1)

Density of water = 1 g/mL

Mass of water = 15 g

Putting values in equation 1, we get:

Given mass of phosphoric acid = 85 g

Molar mass of phosphoric acid = 98 g/mol

Molarity of solution = 15 M

Putting values in above equation, we get:

Volume of phosphoric acid = Volume of solution - Volume of water

Volume of phosphoric acid = [57.82 - 15] mL = 42.82 mL

Mass of phosphoric acid = 85 g

Volume of phosphoric acid = 42.82 mL

Putting values in equation 1, we get:

Hence, the density of phosphoric acid is 1.98 g/mL

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