| Date | May 2018 | Marks available | 2 | Reference code | 18M.3.sl.TZ2.18 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Explain | Question number | 18 | Adapted from | N/A |
Question
Excess acid in the stomach is often treated with calcium carbonate.
Formulate a chemical equation for the neutralization of stomach acid with calcium carbonate.
Calculate the amount, in mol, of stomach acid neutralized by an antacid tablet containing 0.750 g calcium carbonate.
Explain how omeprazole (Prilosec) regulates pH in the stomach.
Markscheme
2HCl(aq) + CaCO3(s) → H2O(l) + CO2(g) + CaCl2(aq)
Accept ionic equation:
2H+(aq) + CO32–(aq) → CO2(g) + H2O(l)
[1 mark]
«\(\frac{{0.750 \times 2}}{{100.09}}\) =» 0.0150 «mol HCl»
[1 mark]
inhibits the secretion of stomach acid/H+
«active metabolites» bind «irreversibly» to «receptors of the» proton pump
Do not accept “hydrogen/H/H2” for “H+”.
Accept “PPI/proton pump inhibitor” for M2.
Accept “H+/K+ ATPase” for “proton pump”.
[2 marks]
