Question

Calculate the molality of a solution containing 20.7 g of Potassium carbonate in 500 mL of solution. Assume that
the density of solution is 1 g mL-1.

Answer 1

Answer:

molar mass of potassium carbonate K2CO3=138 g/mol

no. of moles in 20.7 g K2CO3=20.7/138=0.15

volume of solution=500 ml

density of solution= 1 g/ml

mass of solution= volume*density

                           =500*1=500 g=0.5 kg

as mass of solute is very small in comparison to mass of solution. So we can take mass of solution as the mass of solvent.

molarity=moles of solute/mass of solvent = 0.15/0.5 = 0.3 m

Thanks.