You have a 0.850 M NaCl solution. What is the concentration of NaCl in mass percent? (The density of this solution is 1.05 g/mL).

The answer to the question is

The solution contains 4.73 % by mass of NaCl

Explanation:

To solve this we list out the variables thus

The Molarity of NaCl = 0.850 M,

Density of solution = 1.05 g/mL

Molar mass of NaCl = 58.44 g/mol

Therefore mass of NaCl in he solution = (58.44 g/mol) * (0.850 M) = 49.674 g of NaCl

However the density = 1.05 g/mL or 1050 g/L

Therefore the mass percent of NaCl in 1 liter of solution or 1050 g of solution = (49.674/1050) * 100 = 4.73 %

The concentration of NaCl in mass percent = 4.73 %

4.74 %.

Explanation:

Molar mass of NaCl = 23 + 35.5

= 58.5 g/mol.

Molar concentration = molar mass/volume

Density = mass/volume

Converting g/ml to g/l,

1000 ml = 1 l

= 1.05 g/ml * 1000 ml/1 l

= 1050 g/l

Mass concentration = mass/volume

= molar concentration * molar mass

= 0.85 * 58.5

= 49.7325 g/l.

Comparing the density and the mass concentration in %,

= 49.7325 : 1050

= 4.74 %