Question

molarity of H2So4 solution is 18 moles if density of solution is 1.8 g/cm calculate the molality of solution

Answer 1

molality = mol H2SO4/kg solvent 
molarity = mol H2SO4/L solution 

Using density, 
Mass of the solution = 1.8g/ml * 1000 ml = 1800g 

Molecular weight of H2SO4 = 98g 

Mass of solute (H2SO4) = 18 mol * 98 g = 1764 g 

Mass of solvent = mass of solution - mass of solute 
= 1800 g - 1764 g 
= 36 g = 0.0036 kg 

Molality = mol. H2SO4/ kg of solvent 
= 18 mol/0.0036kg 
= 500 mol/kg