Question

The sulfuric acid (98 g/mol) in a car battery has a density of 1.225 g/cm3 and is 3.75 M. What is the molality, mole fraction and percentage of sulfuric acid by mass in this solution?

Answer 1

Let the solution volume is 1.0L

3.75 M means that 3.75 moles of H2SO4

g H2SO4=3.75 mole x 98=367.5 g H2SO4.

Mass of solute

g solution=1.00L x 103 x 1.225g/ml = 1225 g solution

Mass of solutionMass of solvent = 1225-367.5 = 857.5g water

m= moles of solute / kg of solvent

    = 3.75 moles/0.8575kg

    = 4.37 m

% = g of solute / g of solution

    = 367.5 g/ 1225 g

    = 30%

XH2SO4 =3.75 mol H2SO4

(857.5g/18) mole H2O + 3.75 mol H2SO4

= 0.073