| Date | November 2010 | Marks available | 2 | Reference code | 10N.3.sl.TZ0.D1 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | State | Question number | D1 | Adapted from | N/A |
Question
Dyspepsia, commonly known as indigestion, is due to excess acid in the stomach and can be treated using antacids.
State the name of the acid found in the gastric juices of the stomach.
Two examples of antacids are aluminium hydroxide and calcium carbonate. State the equations to show the action of each antacid.
Markscheme
hydrochloric acid;
\({\text{Al(OH}}{{\text{)}}_{\text{3}}} + {\text{3HCl}} \to {\text{AlC}}{{\text{l}}_{\text{3}}} + {\text{3}}{{\text{H}}_{\text{2}}}{\text{O}}\);
\({\text{CaC}}{{\text{O}}_3} + {\text{2HCl}} \to {\text{CaC}}{{\text{l}}_2} + {\text{C}}{{\text{O}}_2} + {{\text{H}}_2}{\text{O}}\);
Ignore state symbols.
Award [1 max] for correct reactants and products in both equations if equations are not balanced.
Examiners report
The vast majority scored the mark in (a), but a small number of candidates gave the formula for hydrochloric acid rather than writing the name.
In (b) many correct answers were given but it was surprising to see that some candidates did not know the correct chemical formulas and how to balance equations. In some cases candidates wrote an equation for the reaction between aluminium hydroxide and calcium carbonate.
