Question

How many moles of H2SO4 are present in 250 g of an aqueous solution that is 4.8 molal? The density of the solution is 1.58 g/ml.

Answer 1

Answer: 0.815 moles of H2SO4 are present in 250 g of given solution.

Explanation:

STEP1: Calculation of amount of H2SO4 in 250g of an aqueous solution

4.8 molal means 4.8 moles/1000g of an aqueous solution

mass of H2SO4 ---> 98.0768 g/mol times of 4.8 mol = 470.8 g

mass of solution ---> 1000 g (weight of 1L of water) + 470.8 g = 1470.8 g

470.8 g of H2SO4 in----------à 1470.8 g of an aqueous solution

“x” g of H2SO4 in ----------------à 250g of an aqueous solution

x = (470.8 X 250)/1470.8 = 80.02 g

STEP2: Calculation of number of moles in 80.02 g of H2SO4

= (Weight of H2SO4 in 250 g of an aqueous solution)/ (molecular weight of H2SO4)

= (80.02 g) / (98.0768 g/mol)

= 0.815 moles