Question

How many grams of NaCl should be added to 250 grams of waterto make a 0.40 m solution?

Answer 1

Answer:

5.85 grams of NaCl should be added to 250 grams of water to  make a 0.40 m solution.

Explanation:

$molality=\frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{ Mass of solvent (kg)}}$

Mass of NaCl =x

Molar mass of NaCl = 58.5 g/mol

Molality of the solution = 0.40 m

Mass of the solvent = 250 g = 0.250 kg (1g = 0.001 kg)

$0.40 m=\frac{x}{58.5 g/mol\times 0.250 kg}$

$x=0.40 m\times 58.5 g/mol\times 0.250 kg=5.85 g$

5.85 grams of NaCl should be added to 250 grams of water to  make a 0.40 m solution.