1. Antacids Assessment Statement - State and explain how excess acidity in the stomach can be reduced by the use of different bases.

2. Stomach Acidity Stomach cells secrete hydrochloric acid (HCl)  providing an acidic environment (pH of 1-2) Benefits of acidic environment: • kill bacteria • provide optimum pH for digestive enzymes (ex. Pepsin)

3. - IB Questions Q: Identify the substance responsible for low pH of the liquid in the stomach A: hydrochloric acid

4. Stomach Acidity Excess Stomach Acidity Cause: alcohol, smoking, stress, anti- inflammatory drugs Outcomes: acid indigestion – discomfort feeling from too much acid heartburn – acid rising into the esophagus (acid reflux) ulcer – damage to the lining of the stomach wall, results in tissue loss and inflammation http://www.youtube.com/watch?v=EXGHpXlBgZA&safety_mode=true&persist_safety_mode=1&safe=active

5. - IB Questions Q: Explain how heartburn is caused A: Heartburn is caused by the acid rising up to the esophagus

6. What is Antacids? • drugs that work to neutralizeHCl in the stomach • relieve discomforts • adjustthe pH of the stomach to the desire level of acidity

7. Compounds of Antacids • all compounds of antacids are WEAK BASIC Compounds/Ingredients: - metal oxides - metal hydroxides { Al(OH)3 , Mg(OH)2 } - carbonates { CaCO3 } - hydrocarbonates { NaHCO3 }

8. Compounds of Antacids metal oxides/ hydroxides + HCl salt + H2O carbonates/ hydrocarbonates +HCl  salt + H2O + CO2

9. Neutralization of HCl Examples: 1. magnesium oxide 2. magnesium hydroxide 3. aluminum hydroxide 4. calcium carbonate 5. sodium hydrocarbonate Remember to balance the equations!!!

10. Neutralization of HCl • MgO + 2HCl  MgCl2+ H2O • Mg(OH)2 + 2HCl  MgCl2 + 2H2O • Al(OH)3 + 3HCl  AlCl3 + 3H2O • CaCO3 + 2HCl  CaCl2 + H2O + CO2 • NaHCO3 + HCl  NaCl + H2O + CO2

11. - IB Questions Q: What are the metals that used in antacids? A: aluminum, calcium, magnesium, sodium

12. Neutralization of HCl ***Notice the mole ratio of the reactions • the mole ratio determines the effectiveness when comparing compounds Neutralization of HCl with aluminum hydroxide is the most effective - Al can neutralize 3 moles of H+ ions / it has three OH- ions

13. Antacid Formulations Can contains both magnesium and aluminum compounds Why both? - they act as complements of each others

14. Antacid Formulations With metal carbonates and hydrocarbonates ..... .... the production of CO2 gas may cause bloating and flatulence CaCO3 + 2HCl  CaCl2 + H2O + CO2 NaHCO3 + HCl  NaCl + H2O + CO2

15. Antacid Formulations Solutions: 1) antifoaming agents are added to relieve the side effects (ex. dimethicone) 2) ALGINATES are added to prevent reflux into the esophagus

16. Health Hazard!!! High dose  a basic stomach – can cause discomforts, a condition called alkalosis Antacids are not always necessary …. …. frequent use can harmful to heart, kidney, or bones

17. - IB Questions Q: Suggest why potassium hydroxide is not used as an antacid A: KOH is a strong base (alkali) so it would be dangerous for body cells; it is corrosive and would upset the pH

18. The End!