Question

If the azeotropic mixture is 72% perchloric acid by mass, what is the mole percent of water in the azeotrope?

Answer 1

Answer:

Mole percent of water in azeotrope is 69%

Explanation:

Clearly, the azeotrope consists of water and perchloric acid.

So, 72% perchloric acid by mass means 100 g of azeotrope contains 72 g of perchloric acid and 28 g of water.

Molar mass of water = 18.02 g/mol and molar mass of perchloric acid = 100.46 g/mol

So, 72 g of perchloric acid = $\frac{72}{100.46}mol$ of perchloric acid = 0.72 mol of perchloric acid

Also, 28 g of water = $\frac{28}{18.02}mol$ of water = 1.6 mol of water

Hence total number of mol in azeotrope = (1.6+0.72) mol = 2.32 mol of azeotrope

So, mole percent of water in azeotrope = [(moles of water)/(total no of moles)]$\times 100$%

Mole percent of water  = $\frac{1.6}{2.32}\times 100$ % = 69%