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SURVEY OF CHEMISTRY LABORATORY I CHEM 1151L ANTACID EVALUATION

A chemistry lab experiment comparing antacids' ability to neutralize stomach acid using titration with NaOH. Learn about antacids, stomach acid, and the importance of pH balance. Safety precautions are essential during this investigation.

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SURVEY OF CHEMISTRY LABORATORY I CHEM 1151L ANTACID EVALUATION

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  1. SURVEY OF CHEMISTRY LABORATORY I CHEM 1151L ANTACID EVALUATION

  2. CAUTION!!! BE SURE TO WEAR SAFETY GLASSES AT ALL TIMES IN THE LABORATORY NO EXCEPTIONS TO THIS RULE!

  3. ANTACID EVALUATION - To compare commercial preparations (antacids) commonly used to combat acid indigestion - Students will react three different antacids with excess HCl acid - A portion of the acid will be neutralized by the antacids - Amount of unreacted acid will be determined by titration with NaOH base - The least neutralized sample by antacid will require most base

  4. ANTACID EVALUATION - Acid indigestion or heartburn is a common malady in our daily life - Results from foods and drinks - The normal functioning of the stomach in the digestive process requires that acid be present - Stomach acid (called gastric juice) is hydrochloric acid (pH ≈ 1.0) - A prolonged or recurring condition of indigestion may lead to damage of the stomach lining and result in ulcers - Antacids are basic and used to neutralize stomach acid

  5. INDICATOR - An indicator is required to see when enough base has been added to the acid - Phenolphthalein indicator will be used in this experiment - Phenolphthalein is colorless in acidic solutions and pink in basic solutions - End point of titration is reached when solution turns into faint pink upon addition of NaOH - This implies all acid is neutralized by base

  6. 4 ERLENMEYER FLASKS - Obtain 4 clean 125 mL Erlenmeyer flasks

  7. MEASURE HCl ACID - Use a buret to measure 25.00 mL of 1 M HCl into each of the 4 Erlenmeyer flasks

  8. MEASURE HCl ACID - Use a buret to measure 25.00 mL of 1 M HCl into each of the 4 Erlenmeyer flasks

  9. PREPARE ANTACID SAMPLES - Select 3 antacid tablets - Grind each tablet into powder using the mortar and pestle - Mass each tablet with a different weighing paper - Place each in separate flasks and label them - Also mass ~ 0.5 grams of baking soda NaHCO3 into the fourth flask - Be sure to label the flasks

  10. PREPARE ANTACID SAMPLES - Select 3 antacid tablets - Grind each tablet into powder using the mortar and pestle - Mass each tablet with a different weighing paper - Place each in separate flasks and label them - Also mass ~ 0.5 grams of baking soda NaHCO3 into the fourth flask - Be sure to label the flasks

  11. PREPARE ANTACID SAMPLES - Select 3 antacid tablets - Grind each tablet into powder using the mortar and pestle - Mass each tablet with a different weighing paper - Place each in separate flasks and label them - Also mass ~ 0.5 grams of baking soda NaHCO3 into the fourth flask - Be sure to label the flasks

  12. PREPARE ANTACID SAMPLES - Select 3 antacid tablets - Grind each tablet into powder using the mortar and pestle - Mass each tablet with a different weighing paper - Place each in separate flasks and label them - Also mass ~ 0.5 grams of baking soda NaHCO3 into the fourth flask - Be sure to label the flasks

  13. PREPARE ANTACID SAMPLES - Make sure each antacid is completely dissolved - Add 3 – 4 drops of phenolphthalein indicator to each flask

  14. FILL BURET WITH NaOH - Rinse your buret with about 3 – 5 mL of 0.5 M NaOH solution - Fill the buret with the 0.5 M NaOH solution - Use small beaker to fill (do not use funnel)

  15. FILL BURET WITH NaOH - Drain some NaOH to fill the tip - Record the initial reading

  16. TITRATE SAMPLES WITH NaOH - Place one of the flasks under the buret and begin to titrate - Allowing the NaOH to drip steadily into the flask - Swirl flasks continuously - Be careful not to go over the end point (over titrate)

  17. TITRATE SAMPLES WITH NaOH - Pink color will begin to appear and disappear after swirling - Add one drop at a time at this point - Stop when pink color remains for at least 30 seconds (end point is reached) - Read and record the final reading - Do not go past the 50 mL mark (stop and refill if necessary Click on picture to play video

  18. DETERMINE EFFICIENCY NUMBER - Repeat procedure for each of the remaining flaks - Determine the volume of NaOH used for each flask - Calculate the efficiency number for each tablet using the equation below (include appropriate units) - Also record the active ingredients for each tablet from their bottles

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