What mass of sodium hydroxide is required to neutralize 300 g of hydrochloric acid with a mass fraction of HCl = 14%.

1. Let’s write down the reaction equation:

NaOH + HCl = NaCl + H2O.

2. Find the mass of hydrochloric acid, and then its amount:

m (HCl) = (m (solution) * ω (HCl)) / 100% = 300 g * 14% / 100% = 42 g.

n (HCl) = m (HCl) / M (HCl) = 42 g / 36.5 g / mol = 1.15 mol.

3. Using the reaction equation, we find the amount of sodium hydroxide, and then its mass:

n (NaOH) = n (HCl) = 0.15 mol.

m (NaOH) = n (NaOH) * M (NaOH) = 0.15 mol * 40 g / mol = 46 g.

Answer: m (NaOH) = 46 g.