Question

105mL of pure water is saturated withNH₃ gas producing a solutionofdensity 0.9 g/ mL . If this solution contains 30% of NH₃ by weight , calculate its volume .

Answer 1

Let us suppose that the mass of NH₃ = x g

Mass of pure water = 105 g (as density of pure water is 1g/ml, so 105 mL = 105 g)

Mass of solution = (105+x) g

Mass% of solute = [(Mass of NH₃) / (mass of solution)] x 100

30/100 = x/(105+x)

x-0.3x=31.5

0.7x=31.5

x=45 g

Mass of solution = 105+45 = 145 g

Density = Mass/Volume

Volume = Mass/Density

Volume of solution = (145 g / 0.9 g/mL) = 161.11 mL