1. D2: Antacids

2.  D.2.1: State and explain how excess acidity in the stomach can be reduced by the use of different bases  Gastric acid is an acid that is found in the stomach and consists highly of HCl and a pH value of 2.  An Antacid is any substance, generally a base or basic salt, which counteracts stomach’s acidity. Antacids are stomach acid neutralizers. They are weak bases such as metal oxides, hydroxides, carbonates, and hydrocarbonates.  Antacids perform a neutralization reaction. They buffer gastric acid, raising the pH to reduce acidity in the stomach.

3. D2: Antacids - Dyspepsia is a condition where it is hard or difficult for the person to digest food. This is due to excess acid, and can be fought by taking antacids. - Examples of antacids and typical neutralization reactions: - NaCHO 3 (s) + HCl(aq) -----► H 2 O(l) + NaCl(aq) + CO 2(g) - MgO(s) + 2HCl(aq) -----► MgCl 2(aq) + H 2 O(l) - Mg(OH) 2 + 2HCl(aq) -----► MgCl 2 (aq) + 2H 2 O(l) - Al(OH) 3 (s) + 3HCl(aq) -----► AlCl 3 (aq) + 3H 2 O(l)

4. Antacids  bad effects from antacids include:  Carbonates: A chemical reaction between the carbonate and hydrochloric acid may produce carbon dioxide gas. This causes gastric distension which may not be well tolerated. Carbon dioxide formation can also lead to headaches and decreased muscle flexibility.  Aluminum hydroxides: aluminium hydroxide may lead to the formation of insoluble aluminium phosphate complexes, with a risk for decrease the level of phosphate in the blood. It can also soften the person's bones.  Sodium hydro carbonates: intake of sodium hydro carbonates may cause heart failure.