Determine the concentration of acetic acid in a [621171]

Objectives
Determine the concentration of acetic acid in a
commercial vinegar samples
Obtaining eco based vinegar from pumpkin

The history of vinegar
Peoples around theWorld have used vinegar inmany ways, foryears .
One oftheprincipal uses was inthearmy where soldiers used toenergize and treat
infections .Roman soldiers called this refreshing drink posca .They used itregularly
like the Japanese samurai .The addition ofvinegar totheir drinking water had the
additional benefit ofkilling anyinfectious agents that might have been present .

balsamic vinegar witch is superior that
the usual one because it have bioactive
compounds first vinegar recipe handed from father to son
Source: http://www.enzyme -facts.com/vinegar -history.html

The chemical structure of acetic acid
Acetic acid is an simple organic acid that belongs to the class of carboxylic compounds

EXPERIMENTAL PLAN

Types of vinegar
White wine vinegar Ethanol vinegarApple vinegar
MATERIALS

A. Determination of the pH values of vinegar solution
a. The pH meter is calibrated with standard buffer solutions (pH
4.01, 7.0 and 9.2).Steps:
b. Testing of vinegar samples

B.Determination ofSoluble Solids Content ofvinegar
solution, using refract meter
Steps:
a. The refract meter is calibrate with a drop of distilled water.
b. Added a drop of vinegar on refract meter prism.
c. Read the value.
d. Rinsed the prism between samples with distilled water and dried with a soft
tissue.

C.Concentration determination ofacetic acid from vinegars
bytitrimetric method
Steps
a.Preparing the 0.1 M NaOH solution
b.Fill the burette with NaOH standard solution
c.Determination of correction factor of NaOH solution using oxalic acid
d.Titration the vinegar samples (1 ml vinegar + 50 ml distillated water) in the presence
of phenolphthalein indicator
e.Calculated the concentration of acetic acid from vinegar
CH3COOH( aq) + NaOH (aq) –> CH3COONa( aq) + H2O(l)

CH3COOH( aq) + NaOH (aq) –> CH3COONa( aq) + H2O(l)
The reaction stoichiometry is one mole of acetic acid reacting with one mole of sodium
hydroxide, the number of moles of acetic acid in the portion of the vinegar sample titrated is :
moles of acetic acid = ( MNaOH)(VNaOH)
MNaOH is the molarity of the sodium hydroxide solution in moles/L (0.1 M)
VNaOH is the volume of sodium hydroxide solution in liters
The grams of acetic acid in the vinegar sample can be calculated by multiplying the moles
of acetic acid by the molecular weight of acetic acid (MW).
grams of acetic acid = (moles of acetic acid)(MW)
The percent by mass of acetic acid in the vinegar sample is calculated as:
% acetic acid = (grams of acetic acid / grams of vinegar) x 100
By assuming the density of the vinegar sample to be 1.00 g/ mL,
grams of vinegar = (volume of vinegar)(density of vinegar)

Experimental design for obtaining the
pumpkin
(steps of)
❶Anaerobe fermentation:
①Preparing Steps
②Determining the pH
③Determining the Acidity
④Determining the Brix
⑤Determining the UV -Vis
❷Aerobe fermentationOverall time: 4 days

Pumpkin Cutting Blending
Filtering Adding sugar Anaerobe fermentation

RESULTS
3.153.273.32
3.053.103.153.203.253.303.35
Ethanol vinegar White wine vinegar Apple vinegar pH4.605.50
4.65
4.004.204.404.604.805.005.205.405.60
Ethanol vinegar White wine vinegar Apple vinegar Brix grade
12.87
12.12
8.25
02468101214
Ethanol vinegar White wine vinegar Apple vinegar % acetic acid

UV-Vis spectrum of pumpkin extract
250 300 350 400 450 500-0.50.00.51.01.52.02.53.03.54.0Absorbance281 nm305 nm
wavelenght, nm
RESULTS

RESULTS
5.535.695.725.78
5.725.91
5.505.68
5.205.305.405.505.605.705.805.906.00
day 1 day 2 day 3 day 4pH 40 g sugar
25 g sugarpH

RESULTS
12.913.1
4.811.2
10.3
3.8
02468101214
day 1 day 2 day 3Brix grade40 g sugar
25 g sugarBRIX grade

1.081.171.231.351.32
0.961.441.8
00.20.40.60.811.21.41.61.82
day 1 day 2 day 3 day 4acetic acid %40 sugar
25 sugarAcidity

Conclusion
1)Evaluation of physical -chimical properties of commercial vinegar reveled that some
values as are the one written on the label.
2)Regarding to the pumpkin vinegar the process to obtain vinegar takes a long time a