Best Antacid
Purpose:
You will check the neutralization ability of various chemicals by the process of titration. Using the following method you will be able to determine the best antacid. You may also discover a way to determine if milk has been stored properly or is beyond purchase date.
Materials:
- eyedropper
- Tums, baking soda, Alka Seltzer, etc.
- 30 ml of distilled water
- acid of a known strength (molarity). I generally use 0.1 M HCl (hydrochloric acid).
- mortar and pestle
- Phenolphthalein indicator (can be extracted from "Ex Lax" using alcohol)
Procedure:
- Use the mortar and pestle to crush one tablet of antacid.
- Dissolve the antacid in 30 ml of distilled water.
- Add several drops of phenolphthalein.
- Calibrate the eyedropper to find out how many drops equal 1 ml. Be sure to hold the eyedropper vertically when releasing drops.
- Titrate the acid against a known amount of antacid solution. The phenolphthalein indicator will change color from pink to colorless. Be sure to record the amount of acid used and the amount of antacid neutralized.
- Evaporate the water away at room temperature and look at the result. Are crystals present? What type of chemical has been formed and give it's name.
- Check a different antacid and determine which one is best.
Discussion:
What was the best antacid? Did best mean recommended dosage, by weight, by price, etc.? Why is phenolphthalein used when it changes color between pH 8.3 to 10? You can titrate milk by using a base like sodium hydroxide (0.1 M). Check fresh milk and milk that is beyond the purchase date or milk that has been stored in a warm area for some time. What happens to the pH of the milk as it ages? Explain how titration can be used to determine the unknown molarity of an acid or base. Why are HCl and NaOH used for titration instead of organic acids or non-alkali bases?
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You will check the neutralization ability of various chemicals by the process of titration. Using the following method you will be able to determine the best antacid. You may also discover a way to determine if milk has been stored properly or is beyond purchase date.
- Use the mortar and pestle to crush one tablet of antacid.
- Dissolve the antacid in 30 ml of distilled water.
- Add several drops of phenolphthalein.
- Calibrate the eyedropper to find out how many drops equal 1 ml. Be sure to hold the eyedropper vertically when releasing drops.
- Titrate the acid against a known amount of antacid solution. The phenolphthalein indicator will change color from pink to colorless. Be sure to record the amount of acid used and the amount of antacid neutralized.
- Evaporate the water away at room temperature and look at the result. Are crystals present? What type of chemical has been formed and give it's name.
- Check a different antacid and determine which one is best.