How many grams of a 20% sodium hydroxide solution are required to fully react with 100 ml of a 0.5 M solution of iron(III) chloride?
- 30 g
- 15 g
- 60 g
- 40 g
📝 Detailed explanation
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl.n(FeCl₃) = 0.1 L * 0.5 M = 0.05 mol.
n(NaOH) needed = 0.05 * 3 = 0.15 mol.
Mass pure NaOH = 0.15 * 40 = 6 g.
Mass 20% solution = 6 / 0.2 = 30 g.