30 cm of 0.2 mol/dm sodium hydroxide solution is neutralised by hydrochloric acid of concentration 0.25 mol/dm according to NaOH + HCl → NaCl + HO. What volume of the acid is needed?
Answer and explanation
Correct answer: B. 24 cm
- Step 1: Moles of NaOH mol.
- Step 2: From the equation, 1 mol of acid reacts with 1 mol of NaOH, so moles of acid mol.
- Step 3: Volume of acid cm.
Answer
24 cm.
Why not the others: 48 cm: it applies a 1:2 ratio that the equation does not have. 1.5 cm: it multiplies the concentrations and volume. 30 cm: it assumes equal volumes.
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