Chem Project Antacid

CHEMISTRY PROJECT Drug: Antacid Effectiveness Analysis To determine the neutralizing ability of antacids in different brands using back titration 7C Candy Kwok (12) Maggie Lam (13) Cecilia Wu (23)

THEORY ANTI ACID IS A KIND OF MEDICINE THAT USED TO CURE STOMACH ACHE ■ IN THIS EXPERIMENT ,WE WILL PUT THE ANTI ACID IN KNOWN MOLARITY (O.1M)HCl AND IS BACK TITRATED AGAINST STANDARD NaOH SOLUTION. ■

WE CAN DETERMINE THE NEUTRALIZING POWER OF EACH BRAND OF SAMPLE BY RECORDING THE VOLUME OF NaOH USED IN BACK TITRATION ■ THE ONE WHICH USE LESS NaOH IN BACK TITRATION MEANS THAT IS THE STRONGER ■

WEISEN-U

Composition OUTER LAYER (yellowish green)

INNER CORE (white to yellowish white)

Biodiastase 2000…25mg

Methylmethionine Sulfonium Chloride… 25mg

Dried Aluminum Hydroxide Gel…192mg Magnesium Hydroxide…159mg

ACTAL Composition ■ Al(OH)3 216 mg) ■

Unknown

Composition ■ Aluminium/ magnesium hydroxide simethicone ■

Apparatus & reagents used 0.1M NaOH solution ■ 0.1M HCl solution ■ 3 tablets of antacids of different brands ■ Phenophthalein indicator ■ Pipettes and pipette fillers ■ 100ml volumetric flasks ■ Electric balance ■

Apparatus & reagents used Mortars and pestles ■ Hot plates ■ White tiles ■ Thermometer ■ Stop watch ■ Dropper ■ Conical flask ■

Distilled water in wash bottle Tap water. Burettes Filter funnel Labels Glass rods Stands and clamps Beakers

Chemical reactions involved Acid + Base  Salt + Water ■ NaHCO3 + HCl NaCl + H2O + CO2 ■

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CaCO3 + 2HCl CaCl2 + H2O + CO2

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Al(OH) 3 + 3HCl AlCl3 + 3H2O

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Mg(OH) 2 + 2HCl MgCl2 + 2H2O

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No. of moles = Molarity × volume

Procedure

Procedure Transfer an antacid tablet to a clean mortar and crush it in to a fine powder ■ Weigh the mortar filled with fine powder ■ Transfer the powder to a conical flask ■

Weigh the mortar again ■ Dissolve the antacid with 150ml of distilled water by using hot plate ■ Cool the dissolved antacid to room temperature (25℃ ) by immersing it in tap water ■

Transfer the dissolved antacid to a 250ml volumetric flask. ■ Fill the flask to the mark with water. ■ Cap the flask and invert several times to mix well. ■

Use a pipette to transfer 25ml of dilute HCl solution to the conical flask that HCl is in excess. ■ Add the dissolved antacid to the conical flask ■ Swirl the flask until the liquid become slightly cloudy. ■

Clean, rinse and fill a burette with NaOH solution ■ Release a small amount of NaOH solution to leave the tip entirely filled. ■ Record the initial NaOH volume reading from the burette. ■ Place a white tile under the flask. ■

Add 3-4 drops of phenothalein to the flask. ■ Add NaOH solution from the burette with continuous swirling until the colour of the liquid change from colourless to pale pink. ■ Record the final NaOH volume reading from the burette. ■ Repeat the experiment by using antacids in different brands. ■

NO. OF MOLE OF HCl NEUTRALIZED BY EACH SAMPLE WEISEN U:(2.559/1000)mol ■ TAITAN:(2.12/1000)mol ■ HYDROSOIL:(1.24/1000)mol ■

Source of error Some ingredients in the anti-acid may affect the pH value of the mixture and the result. ■ Loss of active ingredient during transferring. ■ The meniscus didn’t sit at the graduated mark of the burette or pipette. ■ The coatings of anti-acid may not dissolve in acid or dissolve slowly. ■ The other ingredients may affect the solubility of the bases inside the anti-acid ■

The reaction may not be complete. ■ Error in taking burette reading (0.05 cm3). ■ The end point may not equal to the equivalence point. ■ The antacid was coloured and the solution was cloudy and it was difficult to observe the colour change and hence the end point may be overshoot. ■ During the heating process, some of the liquid may evaporate. ■

Improvements Sufficient time should be given for the reaction of acid and base. ■ pH metre should be used to detect the end point. ■