Question 23M.3.HL.TZ1.17
| Date | May 2023 | Marks available | [Maximum mark: 3] | Reference code | 23M.3.HL.TZ1.17 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Show, Write | Question number | 17 | Adapted from | N/A |
Magnesium carbonate and aluminium hydroxide are two antacids.
Write two equations showing how these antacids neutralize excess hydrochloric acid.
Magnesium carbonate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Aluminium hydroxide: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
[1]
MgCO3(s) + 2HCl(aq) → MgCl2(aq) + H2O(l) + CO2(g)
AND
Al(OH)3(s) +3HCl(aq) → AlCl3(aq) + 3H2O(l) ✓
Accept appropriate ionic equations.
Do not accept H2CO3 as a product of first reaction.
Ignore equilibrium arrows.
Show by calculation that a 2.00 g tablet of aluminium hydroxide would neutralize more hydrochloric acid than a 2.00 g tablet of magnesium carbonate.
[2]
«n(MgCO3) = 2.00g/84.32 g mol−1=» 0.0237« mol»
AND
«n(Al(OH)3) = 2.00g/78.01 g mol−1 =» 0.0256 «mol» ✓
«0.0237n(MgCO3) × 2 =» 0.0474 «n(HCl) neutralised»
AND
«0.0256 n(Al(OH)3) × 3 =» 0.0768 «n(HCl) neutralised» ✓
Award [1 max] for any two correct calculations.
