1. (D2) Antacids
Sarah Black

2. Background:
Humans naturally secrete gastric juices containing HCl, which…
suppress growth of harmful bacteria
help digestion by hydrolysing protiens into amino acids
For various reasons (stress, over-eating) sometimes excess acid is produced, causing indigestion.
Antacids remedy this excess acidity.

3. About Antacids: Antacids are bases
Usually metal oxides, hydroxides, carbonates, or hydrogen carbonates
Over-the-counter antacids usually contain Al(OH)3, Mg(OH)2, CaCO3, and NaHCO3 as active ingredients.
They may also contain alginates (prevent acid reflux), and anti-foaming agents such as dimethicone.

4. Action of Antacids: MgO(s) + 2HCl(aq)  MgCl2(aq) + H2O(l)
Mg(OH)2(aq) + 2HCl(aq)  MgCl2(aq) + 2H2O(l)
Al(OH)3(s) + 3HCl(aq)  AlCl3(aq) + 3H2O(l)
CaCO3(s) + 2HCl(aq)  CaCl2(aq) + H2O(l) + CO2(g)
NaHCO3(aq) + HCl(aq)  NaCl(aq) + H2O(l) + CO2(g)
Mg2Si3O8(s) + 4HCl(aq)  3SiO2(aq) + 2H2O(l) + 2MgCl2(aq)

5. Side Effects of Antacids:
Aluminum hydroxide may cause constipation.
Aluminum ions can prevent uptake of phosphate ions due to precipitation of aluminum phosphate.
Magnesium hydroxide has laxative properties.
Calcium carbonate may result in kidney stones.
Sodium ions may lead to hypertension.
Excess use of sodium hydrogen carbonate may lead to alkalosis (basic stomach) and fluid retention.
Repeated use of calcium carbonate as an antacid may lead to excessive amounts of calcium ions being absorbed into the body.