What is the molar concentration of a solution containing 3.7 g of sodium hydroxide in 100 g.

Given:
m solution (NaOH) = 100 g
m (NaOH) = 3.7 g

To find:
See (NaOH) -?

Decision:
1) M (NaOH) = Mr (NaOH) = Ar (Na) * N (Na) + Ar (O) * N (O) + Ar (H) * N (H) = 23 * 1 + 16 * 1 + 1 * 1 = 40 g / mol;
2) n (NaOH) = m (NaOH) / M (NaOH) = 3.7 / 40 = 0.0925 mol;
3) ω (NaOH) = m (NaOH) * 100% / m solution (NaOH) = 3.7 * 100% / 100 = 3.7%;
4) ρ solution (NaOH) = 1.0395 g / ml (according to the table);
5) V solution (NaOH) = m solution (NaOH) / ρ solution (NaOH) = 100 / 1.0395 = 96.2001 ml = 0.0962 L;
6) Cm (NaOH) = n (NaOH) / V solution (NaOH) = 0.0925 / 0.0962 = 0.9615 mol / L.

Answer: The molar concentration of NaOH is 0.9615 mol / L.