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# General Chemistry Lab II (F24 Sec05) ## Antacid Analysis ### Summary of the Procedure * Prepare three clean conical flasks and label them sample 1, 2, and 3. * Add approximately 0.2g of well-pulverized antacid sample to each flask, recording the mass to 0.001g. * Add exactly 25.00 mL of H...

# General Chemistry Lab II (F24 Sec05) ## Antacid Analysis ### Summary of the Procedure * Prepare three clean conical flasks and label them sample 1, 2, and 3. * Add approximately 0.2g of well-pulverized antacid sample to each flask, recording the mass to 0.001g. * Add exactly 25.00 mL of HCl to each flask using a pipette, recording the actual molar concentration. Rinse the pipette twice with HCl before pipetting. * Boil the solutions gently for 2-3 minutes to remove dissolved CO2. * Cool the solutions for about 5 minutes and add 5 drops of bromophenol indicator to each flask. * Prepare a buret for titration. Rinse the buret twice with distilled water, then twice with NaOH. Fill the buret with NaOH (approximately 0.00 mL), and record the actual molar concentration of NaOH. * Record the initial buret reading. Titrate sample 1 with standardized NaOH solution until the solution just barely turns blue. Record the final buret reading at the endpoint. * Repeat the titrations for flasks 2 and 3. * Note: No need to refill the buret for each titration. Use the final reading from the previous titration as the initial reading for the next. Ensure there is sufficient NaOH in the buret (minimum 50.00 mL). ### Points to Remember * Significance of back titration * Color of the indicator at different pH levels * Moles of bases present in the antacid * Moles of unreacted acid * Moles of bases per gram of the antacid **Additional Notes:** * Accuracy * Indirect measurement * Complex samples * Quantitative analysis * Precipitation reactions