Question

1. explain how you would make 100 mL of a 2.0% (w/v) solution of sodium chloride?

Answer 1

1.

Percent (mass/volume) of the solution = (mass of the solute / volume of the solution) x 100

Given, percent of NaCl (m/v) solution = 2.0 %

Volume of solution = 100 ml

Plugging in the numbers in the formula we get,

2.0 = (mass of NaCl/ 100) x 100

Mass of NaCl = (2.0 x 100)/100 = 2 g

So we would dissolve 2g NaCl(s) in 100 ml water to form a 2.0% NaCl solution.

2.

Percent (mass/volume) of the solution = (mass of the solute / volume of the solution) x 100

Given, percent of MgSO₄ (m/v) solution = 1.6%

Volume of solution = 250 ml

Plugging in the numbers in the formula we get,

1.6 = (mass of MgSO₄/ 250) x 100

Mass of MgSO₄ = (1.6 x 250)/100 = 4 g

3.

Percent (mass/volume) of the solution = (mass of the solute / volume of the solution) x 100

Given, mass of CuSO₄ = 2.7 g

Volume of solution = 75 ml

Percent (mass/volume) of the solution = (2.7 g/ 75 ml) x 100 = 3.6%