200 g of sodium hydroxide solution with a mass fraction of alkali of 40% entered into a reaction with sulfuric acid.

200 g of sodium hydroxide solution with a mass fraction of alkali of 40% entered into a reaction with sulfuric acid. Calculate the mass of the salt formed. H2SO4 + NaOH → Na2SO4 + H2O

1. Let’s illustrate the reaction:
2NaOH + H2SO4 = Na2SO4 + 2H2O;
2. Using the value of the mass fraction of sodium alkali, we calculate its mass in solution:
m (NaOH) = w (NaOH) * m (solution) = 0.4 * 200 = 80 g;
3. Let’s calculate the chemical amount of sodium hydroxide:
n (NaOH) = m (NaOH): M (NaOH);
M (NaOH) = 23 + 17 = 40 g / mol;
n (NaOH) = 80: 40 = 2 mol;
4. The amounts of hydroxide and sulfate are 2: 1:
n (Na2SO4) = n (NaOH): 2 = 2: 2 = 1 mol;
5. Knowing the amount, we calculate the mass of the salt obtained:
m (Na2SO4) = n (Na2SO4) * M (Na2SO4);
M (Na2SO4) = 2 * 23 + 32 + 4 * 16 = 142 g / mol;
m (Na2SO4) = 1 * 142 = 142 g.
Answer: 142 g.