Question

Calculate the molality of 1 lt. solution of 93% sulphuric acid .The density of the solution is 1.84 gram per mole

Answer 1

93 % H2SO4 means 93g of H2SO4 is present in 100cc of solution.

Since volume of solution is 1000 ml,

so, amount of H2SO4 in 1000ml solution = (93/100)*1000 = 930 g/litre.

Also density is given 1.84g/mol

Mass of the solution = density x volume = 1.84 x 1000 = 1840 g

therefore, wt of solvent = 1840 - 930 = 910 g

Molecular wt, of H2SO4 = 1*2 + 32 + 4*16 = 98

So, molality = moles of solute / kilograms of solvent.

= (930/98) / (910/1000)

= 930*1000 / 98*910

= 10.43 mol / kg