Group Project 2014CHEM 11141

2012/2013

Finding the acid amount in  Vinegar,

Lime, Garcinia (Goraka),

Tamarind (Siyambala), & Biliimbi (Billin).

ObjectivesUsing the knowledge of Acid –Base

titrations ; Weak acid –Strong Base Titrations to determine the acid value of many natural samples (fruits)

To develop Presentation skills , how to present a project.

Introduction

TitrationsAcid Base TitrationsStrong Base – Weak

Acid Titrations

Indicators used is

Phenolphthalein

LimeLime / Citrus aurantifolia , a citrus fruit which is

typically round containing sour , Juicy, acidic and flavorful pulp

Citric acid is a weak organic acid with the formula C₆H₈O₇ : 2-hydroxypropane-1,2,3-tricarboxylic acid

Ascorbic acid is a naturally occurring organic acid. A white solid. : (5R)-[(1S)-1,2-dihydroxyethyl]-3,4-dihydroxyfuran-2(5H)-one

Ascorbic acid Citric acid

TamarindTamarind / Tamarindus indica , edible , pod-like fruit Rich source of Ascobic Acid, Tartaric acid, non-

starch polysaccharides .Tartaric acid is a white crystalline diprotic acid which

is asymmetric, Ability to rotate polarized light : 2,3-dihydroxybutanedioic acid

Tartaric acidAscobic Acid

Garcinia (Goraka)Garcinia cambogia/ Brindle berry -

Commonly used in culinary. Hydroxycitric acid, the purported active

component and most common acid present in Garcinia.

Hydroxycitric acid (HCA) is a derivative of citric acid : : 1,2-dihydroxypropane-1,2,3-tricarboxylic acid

Hydroxycitric acid

VinegarVinegar is a liquid consisting mainly of Acetic

Acid & Water.Acetic acid / Ethanoic acid is an Organic

compound with the chemical fomular CH3COOH . It is a colourless liquid.

Undiluted is also called Glacial Acetic acid.

Acetic acid

Billimbi (Billin)Bilimbi / Averrhoa bilimbi - tree sorrel , have a

pH of 4.47Ascorbic acid is a naturally occurring in

bilimbi and it is the main Acid Present in bilimbi fruit

Ascobic Acid

MATERIALSGLASS WEAR & EQUIPMENTBurettes ( 50.00mL)Pipettes(25.00mL & 10.00mL)Volumetric flasks (250.00mL &

100.00mL)BeakersTitration flasksFunnelCeramic Mortar & PestleBurette & Funnel standsDroppersFilter papersPipette fillersTest tubeMeasuring CylinderDigital Balance

CHEMICALSH2SO4 (0.1M)NaOH (0.1M)Lime extractVinegarBillimbi

extracrTamarind

extractGarnia

ExtractPhenolphthale

inDistilled

water

MethodSeeds of the test sample fruits were removed and weight was measured

All the solid samples/ Fruits were chopped to extract high amount of extractive from the

sample

Extracted liquids /pastes were taken in to a beaker and diluted to a known volume using

distilled water

Extractive was filtered using filtration(Gravity /Vacuum)

Extracted solutions were diluted again using known volume of distilled water

Known volume from the sample solution was pipette out to a titration flask

Using Phenolphthalein as the indicator back titration was done adding NaOH (0.1M) excess to the titration flask/ titrand and

H2SO4 (0.22M) as the titrant

Blank and Duplications were done and the End points were recorded

Sample

Volume of H2SO4 (0.22M/mL)

Sample NaOH (0.1M)

Observation

Trial 1 Trial 2 Trial 3Volume

(mL)Volume

(mL)

Blank 12.40 mL 12.20 mL

- 10.00 mL 25.00 mL Purple Color solution to

colorless solution

Lime Sample

4.30 mL 4.50 mL - 5.00 mL 25.00 mLPurple Color solution

to lightYellowish-Green solution

Garcinia Sample

6.30 mL 6.65 mL - 05.00 mL 55.00 mLPurple Color solution to light Brown color

solution

Tamarind sample

9.90 mL 9.70mL 10.00 mL 10.00 mL 50.00 mLPurple Color solution

to light Yellowish- Brown solution

Vinager sample

5.70 mL 5.80 mL - 10.00 mL 45.00 mLPurple Color solution

to white color solution

Billimbi sample 4.50 mL 4.30 mL 4.70 mL 10.00 mL 25.00 mL

Purple Color solution to Yellowish solution

Results

Discussion

According to the experiment : Acetic acid concentration in vinegar is 0.197 mol L-1 acids contain in

the sample is “Acetic acid” a monoprotic acid.

Acid Concentration in 14.77g of Garcinia sample is 0.224 mol kg-1 acids contain in the sample is “Hydroxycitric acid” ,which is a direvertive of citric acid.

Acid Concentration of acid in bilimbi sample is 0.0579 mol kg-1 acids contain in the sample is “Ascorbic Acid” which is called as Vitamin C

Acid Concentration in 13.42g of Tamarind sample is 0.1364 mol kg-1 acids contain in the sample are “Tartric Acid and Ascorbic acid”

Acid Concentration in the liquid pulp of the Lime sample is 0.2538 mol kg-1 acids contain in the sample are “Citric Acid and Ascorbic Acid”

In most of the samples the most unique Acid Contained was Ascorbic Acid , the anion of the acid is called Ascorbate ion or Vitamin C

Why the filtration was done?

It helps to remove the particles and to give a clear solution.

This would help to determine the color change of the indicator.

Vacuum filtration was done to the Goraka sample for an efficient filtration.

Color changes that occurred at the end points

Phenolphthalein was used as the indicator. Lime sample Magenta Yellowish-Green solution

Vinegar sample Magenta white color solution

Bilimbi sample Magenta Yellowish solution

Tamarind sample Magenta Yellowish- Brown solution

Goraka sample Magenta Brown color solution

Why the color change “Not ! Magenta to Colorless”

Color change was not easy because of the background Matrix

Why the blanks were done?

Samples may contain impurities. The titrant would react with them too. The get the correct amount the titrant reacted, a blank is needed to be done, but for this titration blank was mainly done to standardize the acid using for titrations because distilled water does not contain acid or anything.

Acid Values are not correct or accurate

These acid values are not 100% correct because of many errors (titration ,Calibration, Avoidable ,Non Avoidable )

And Because of the methods used( Filtration , Acid-Base Titration, Indicators)

Experimented only in one condition, few samples, not an average of many samples from different areas, different “sub species”, whether ripe fruits or Raw fruits.

Acid values can be different from each other because of the above reasons.

Errors occurred during experimentsWeighing errors.Errors occurred when diluting H2SO4(3 M)

and NaOH(1 M).Errors occurred when detecting the end

points.Errors occurred while reading the meniscus

in the burette.

Conclusion According to the experiment :Acetic acid concentration in vinegar

= 0.197 mol L-1

Acid Concentration in 14.77 g of Garcinia sample

= 0.224 mol kg-1

Weight percentage of acid in bilimbi sample

= 0.0579 mol kg-1

Acid Concentration in 13.42 g of Tamarind sample

= 0.1364 mol kg-1

Acid Concentration in 46.40 gof Lime sample

= 0.2538 mol kg-1

Reference http://www.faculty.ucr.edu/~legneref/botany/trofruit.htm ( 08- 06-2014) http://www.crfg.org/pubs/ff/tamarind.html ( 08- 06-2014) http://www.healthline.com/natstandardcontent/garcinia-hydroxycitric-acid ( 08- 06-

2014) https://www.hort.purdue.edu/newcrop/morton/bilimbi.html ( 08- 06-2014) http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-29452001000200045

( 08- 06-2014) http://wwwchem.csustan.edu/consumer/vinegar/analysis.htm ( 08- 06-2014) http://www.culturesforhealth.com/testing-acidity-strength-vinegar ( 08- 06-2014) http://chemwiki.ucdavis.edu/Analytical_Chemistry/Quantitative_Analysis/Titration

( 08- 06-2014) http://www.chemguide.co.uk/physical/acidbaseeqia/phcurves.html ( 08- 06-2014) http://chemwiki.ucdavis.edu/Analytical_Chemistry/Quantitative_Analysis/Titration/T

itration_Of_A_Weak_Acid_With_A_Strong_Base ( 08- 06-2014)

http://www.chem.ufl.edu/~itl/4411/lectures/lec_z2.html ( 08- 06-2014) http://www.fulkersonwinery.com/product-detail/chemicals/citric-acid-2-oz

( 08- 06-2014) 

GROUP MEMBERS

UpekshaKasun WekasingheDulariVirangaSupunThilinaSuranjith