Chapter 15: Antacids - Additional OTC Drugs
● Antacid Medications - Mostly OTC, but prescription needed for acid reflux drugs
● pH - the symbol for acidity, represents the 'power of the Hydrogen (or Hydronium) ion'
○ The pH of a solution is a measure of the acidity of that solution.
● pH of Neutral Water
○ Molarity (moles/L) of the proton(hydronium ion).
○ [H3O+] or [H+] = 0.0000001M = 1 x 10 M
pH = - log
Express concentration. as power of 10 = - log(10 )
Reverse the sign = +7
● The pH of an acidic solution is less than 7. The pH of a neutral solution equals 7. The pH
of a basic solution is greater than 7
● pH of 1 is 10 times more acidic than a pH of 2 and 100 times more acidic than a pH of 3.
A pH of 14 is 10 times more basic than a pH of 13 and 100 times more acidic than a pH
● Alka Seltzer - Effervescent antacid and pain reliever!
○ Hydrolysis of sodium bicarbonate produces a weak acid H C2 (N3OH), so the
resulting solution is basic and a strong base
● TUMS (for the stomach) - Other over the counter drug
○ Active ingredient is CaCO3insoluble in water, so it is in a chewable form
● Pepcid - Active ingredients: CaCO (800mg) andMg(OH) ; 165mg per tablet.
○ Maximum 2 per day
○ Also chewable due to low CaCO3 solubility
● Put sugar in chewable tablets to make them taste better
● Baking soda:
○ Is pure sodium bicarbonate NaHCO 3
○ When dissolved in water, no evolution of at room temperature.
○ Need acid to cause this evolution (ie citric acid) from the lemon, acting on the
● Arm & Hammer Baking soda
○ Contains only sodium bicarbonate powder
○ Can be used as an OTC antacid for acid indigestion only but, it is High sodium,
and since CO 2iven off when combined with stomach acid, it can cause acid
● pH of Blood:
○ If pH drops, eg. during illness, the3[H O+] begins to increase but will react with
HCO -3to form H 2O ,3ie. CO 2 which is exhaled. Or the reverse if pH of blood
○ [H CO ] is maintained by exhaling / inhaling CO
2 3 2
● LeChatelier’s Principle:
○ H2O + CO, -> H 2O 3
○ If more CO2 is produced (ie hyperventilation) , then body reacts to produce