CHEMISTRY PROJECTCHEMISTRY PROJECT

7C Candy Kwok (12)7C Candy Kwok (12)

Maggie Lam (13)Maggie Lam (13)

Cecilia Wu (23)Cecilia Wu (23)

Drug: Antacid Effectiveness Analysis Drug: Antacid Effectiveness Analysis

To determine the neutralizing ability of antacids To determine the neutralizing ability of antacids in different brands using back titrationin different brands using back titration

THEORYTHEORY

ANTI ACID IS A KIND OF MEDICINE ANTI ACID IS A KIND OF MEDICINE THAT USED TO CURE STOMACH THAT USED TO CURE STOMACH ACHE ACHE

IN THIS EXPERIMENT ,WE WILL PUT IN THIS EXPERIMENT ,WE WILL PUT THE ANTI ACID IN KNOWN THE ANTI ACID IN KNOWN MOLARITY (O.1M)HCl AND IS BACK MOLARITY (O.1M)HCl AND IS BACK TITRATED AGAINST STANDARD TITRATED AGAINST STANDARD NaOH SOLUTION.NaOH SOLUTION.

WE CAN DETERMINE THE WE CAN DETERMINE THE NEUTRALIZING POWER OF EACH NEUTRALIZING POWER OF EACH BRAND OF SAMPLE BY RECORDING BRAND OF SAMPLE BY RECORDING THE VOLUME OF NaOH USED IN THE VOLUME OF NaOH USED IN BACK TITRATIONBACK TITRATION

THE ONE WHICH USE LESS NaOH IN THE ONE WHICH USE LESS NaOH IN BACK TITRATION MEANS THAT IS BACK TITRATION MEANS THAT IS THE STRONGERTHE STRONGER

WEISEN-UWEISEN-U

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

Composition

ACTALACTAL

CompositionComposition Al(OH)Al(OH)33 216 mg) 216 mg)

UnknownUnknown

CompositionComposition Aluminium/ magnesium hydroxide Aluminium/ magnesium hydroxide

simethiconesimethicone

Apparatus & reagents usedApparatus & reagents used

0.1M NaOH solution0.1M NaOH solution 0.1M HCl solution0.1M HCl solution 3 tablets of antacids of different brands3 tablets of antacids of different brands Phenophthalein indicatorPhenophthalein indicator Pipettes and pipette fillersPipettes and pipette fillers 100ml volumetric flasks100ml volumetric flasks Electric balanceElectric balance

Apparatus & reagents usedApparatus & reagents used

Mortars and pestlesMortars and pestles Hot platesHot plates White tilesWhite tiles ThermometerThermometer Stop watchStop watch Dropper Dropper Conical flaskConical flask

Distilled water in wash bottleDistilled water in wash bottleTap water.Tap water.Burettes Burettes Filter funnelFilter funnelLabelsLabelsGlass rodsGlass rodsStands and clampsStands and clampsBeakersBeakers

Chemical reactions involvedChemical reactions involved

Acid + Base Acid + Base Salt + Water Salt + Water NaHCONaHCO33 + HCl + HCl NaCl + HNaCl + H22O + COO + CO22

CaCOCaCO33 + 2HCl + 2HCl CaClCaCl22 + H + H22O + COO + CO22

Al(OH)Al(OH) 3 3 + 3HCl + 3HCl AlClAlCl33 + 3H + 3H22OO

Mg(OH)Mg(OH) 2 2 + 2HCl + 2HCl MgCl MgCl22 + 2H + 2H22OO

No. of moles = Molarity × volume No. of moles = Molarity × volume

ProcedureProcedure

ProcedureProcedure

Transfer an antacid tablet to a clean mortar Transfer an antacid tablet to a clean mortar and crush it in to a fine powderand crush it in to a fine powder

Weigh the mortar filled with fine powderWeigh the mortar filled with fine powder Transfer the powder to a conical flaskTransfer the powder to a conical flask

Weigh the mortar againWeigh the mortar again Dissolve the antacid with 150ml of distilled Dissolve the antacid with 150ml of distilled

water by using hot platewater by using hot plate Cool the dissolved antacid to room Cool the dissolved antacid to room

temperature (25 ) by immersing it in tap ℃temperature (25 ) by immersing it in tap ℃waterwater

Transfer the dissolved antacid to a 250ml Transfer the dissolved antacid to a 250ml volumetric flask. volumetric flask.

Fill the flask to the mark with water.Fill the flask to the mark with water. Cap the flask and invert several times to Cap the flask and invert several times to

mix well. mix well.

Use a pipette to transfer 25ml of dilute HCl Use a pipette to transfer 25ml of dilute HCl solution to the conical flask that HCl is in solution to the conical flask that HCl is in excess.excess.

Add the dissolved antacid to the conical Add the dissolved antacid to the conical flaskflask

Swirl the flask until the liquid become Swirl the flask until the liquid become slightly cloudy. slightly cloudy.

Clean, rinse and fill a burette with NaOH Clean, rinse and fill a burette with NaOH solutionsolution

Release a small amount of NaOH solution Release a small amount of NaOH solution to leave the tip entirely filled.to leave the tip entirely filled.

Record the initial NaOH volume reading Record the initial NaOH volume reading from the burette. from the burette.

Place a white tile under the flask. Place a white tile under the flask.

Add 3-4 drops of phenothalein to the flask.Add 3-4 drops of phenothalein to the flask. Add NaOH solution from the burette with Add NaOH solution from the burette with

continuous swirling until the colour of the continuous swirling until the colour of the liquid change from colourless to pale pink. liquid change from colourless to pale pink.

Record the final NaOH volume reading from Record the final NaOH volume reading from the burette.the burette.

Repeat the experiment by using antacids in Repeat the experiment by using antacids in different brands.different brands.

NO. OF MOLE OF HCl NO. OF MOLE OF HCl NEUTRALIZED BY EACH SAMPLENEUTRALIZED BY EACH SAMPLE

WEISEN U:(2.559/1000)molWEISEN U:(2.559/1000)mol TAITAN:(2.12/1000)molTAITAN:(2.12/1000)mol HYDROSOIL:(1.24/1000)molHYDROSOIL:(1.24/1000)mol

Source of errorSource of error Some ingredients in the anti-acid may affect the pH value Some ingredients in the anti-acid may affect the pH value

of the mixture and the result.of the mixture and the result. Loss of active ingredient during transferring.Loss of active ingredient during transferring. The meniscus didn’t sit at the graduated mark of the The meniscus didn’t sit at the graduated mark of the

burette or pipette.burette or pipette. The coatings of anti-acid may not dissolve in acid or The coatings of anti-acid may not dissolve in acid or

dissolve slowly.dissolve slowly. The other ingredients may affect the solubility of the The other ingredients may affect the solubility of the

bases inside the anti-acid bases inside the anti-acid   

The reaction may not be complete. The reaction may not be complete. Error in taking burette reading (0.05 cmError in taking burette reading (0.05 cm33).). The end point may not equal to the equivalence The end point may not equal to the equivalence

point.point. The antacid was coloured and the solution was The antacid was coloured and the solution was

cloudy and it was difficult to observe the colour cloudy and it was difficult to observe the colour change and hence the end point may be overshoot.change and hence the end point may be overshoot.

During the heating process, some of the liquid may During the heating process, some of the liquid may evaporate.evaporate.

ImprovementsImprovements

Sufficient time should be given for the Sufficient time should be given for the reaction of acid and base.reaction of acid and base.

pH metre should be used to detect the end pH metre should be used to detect the end point. point.