Today we will see how to make project on 'determining amount of acetic acid in vinegar' this project is only for class 12th student and this project is belongs to 'Chemistry' in this project we will cover following steps
1. Aim
2. Objective
3. Introduction
4. Apparatus
5. Theory
6. Experimental Procedure
7. Experiment 1
8. Experiment 2
9. Experiment 3
10. Result
11. Precautions
OBJECTIVE
The goal of this project is to determine the amount of Acetic Acid in different types of vinegar using titration with a coloured pH indicator to determine the endpoint
INTRODUCTION
About Vinegar:
Vinegar is a solution made from the fermentation of ethanol
(CH3CH2O H ) , which in turn was previously fermented from sugar. The fermentation of ethanol results in the production of acetic acid (CH3COOH). There are many different types of vinegar, each starting from a different original sugar source ( e.g., rice, wine, malt, etc.) . The amount of acetic acid in vinegar can vary, typically between 4 to 6% for table vinegar, but up to three times higher ( 18%) for pickling vinegar .
Titration introduction:
In this project, I have determined the amount of acid in
different vinegars using titration, a common technique in
chemistry. Titration is a way to measure the unknown amount of a chemical in a solution (the titrant) by adding a measured amount of a chemical with a known concentration (the titrating solution). The titrating solution reacts with the titrant, and the endpoint of the reaction is monitored in some way. The concentration of the titrant can now be calculated from the amount of titrating solution added, and the ratio of the two chemicals in the chemical equation for the reaction.
Titration theory:
To measure the acidity of a vinegar solution, we can add enough hydroxyl ions to balance out the added hydrogen ions from the acid. The hydroxyl ions will react with the hydrogen ions to produce water. In order for a titration to work, we need three things:
1. a titration solution (contains hydroxyl ions with a precisely known concentration),
2. a method for delivering a precisely measured volume of the titrating solution, and
3. a means of indicating when the endpoint has been reached. For the titrating solution, we'll use a dilute solution of sodium hydroxide (NaOH). Sodium hydroxide is a strong base, which means that it dissociates almost completely in water . So for every NaOH molecule that we add to the solution,we can expect to produce a hydroxyl ion.
Performing titration:
To dispense an accurately measured volume of the titrating
solution, we will use a burette. A burette is a long tube with a valve at the bottom and graduated markings on the outside to measure the volume contained in the burette. The burette is mounted on a ring stand, directly above the titrant solution . Solutions in the burette tend to creep up the sides of the glass at the surface of the liquid. This is due to the surface tension of water. The surface of the liquid thus forms a curve, called a meniscus. To measure the volume of the liquid in the burette, always read from the bottom of the meniscus.
Indicators:
In this experiment, we will use an indicator solution called
phenolphthalein. Phenolphthalein is colourless when the solution is acidic or neutral. When the solution becomes slightly basic, phenolphthalein turns pinkish, and then light purple as the solution becomes more basic. So when the vinegar solution starts to turn pink, we know that the titration is complete.
APPARATUS
To do this experiment we will need the following materials and equipment:
➔Vinegar, three different types.
➔Distilled water
➔Small funnel
➔0.5% Phenolphthalein solution in alcohol (pH indicator
solution)
➔0.1 M sodium hydroxide solution
➔125 mL Conical flask
➔25 or 50 mL burette
➔10 mL graduated cylinder
➔Ring stand
➔Burette clamp
THEORY
Required amount of sodium hydroxide (NaOH) can be calculated using the following formula:
W= Molarity X Molar Mass X Volume (cm3)
1000
Molar mass of NaOH = 40 g/mol
= 0.5 X 40 X 500
1000
= 10 g
The acetic acid content of a vinegar may be determined by
titrating a vinegar sample with a solution of sodium hydroxide of known molar concentration (molarity).
CH3COOH(aq) + NaOH(aq) --> CH3COONa(aq) + H2O(l)
(acid) + (base) --> (salt) + (water)
At the end point in the titration stoichiometry between the
both solution lies in a 1:1 ratio.
MCH3COOH X VCH3COOH=M NaOH X V NaOH
Strength of acid in vinegar can be determined by the following formula: Strength of acetic acid =MCH3COOH X 60
Indicator:- Phenolphthalein
End Point:- Colourless to pink
EXPERIMENTAL PROCEDURE
1. Pour 1.5 ml of vinegar in an Conical flask.
2. Add distilled water to dissolve the vinegar so that the
volume of the solution becomes 20 mL.
3. Add 3 drops of 0.5% phenolphthalein solution.
4. Use the burette clamp to attach the burette to the ring
stand. The opening at the bottom of the burette should be just above the height of the Conical flask we use for the vinegar and phenolphthalein solution.
5. Use a funnel to fill the burette with a 0.1 M solution of
sodium hydroxide.
6. Note the starting level of the sodium hydroxide solution in
the burette. Put the vinegar solution to be titrated under the
burette.
7. Slowly drip the solution of sodium hydroxide into the vinegar solution. Swirl the flask gently to mix the solution, while keeping the opening underneath the burette.
8. At some point we will see a pink colour in the vinegar solution when the sodium hydroxide is added, but the colour will quickly disappear as the solution is mixed. When this happens, slow the burette to drop-by-drop addition.
9. When the vinegar solution turns pink and remains that colour even with mixing, the titration is complete. Close the tap (or pinch valve) of the burette.
10. Note the remaining level of the sodium hydroxide solution in the burette. Remember to read from the bottom of the meniscus.
11. Subtract the initial level from the remaining level to figure out how much titrating solution we have used.
12. For each vinegar that we test, repeat the titration at least
three times.
EXPERIMENT
Take the laboratory vinegar in the conical flask and do the
titration with NaOH as mentioned.
OBSERVATIONS
CALCULATIONS:-
We know that:-
MCH3COOH X V CH3COOH=M NaOH X V NaOH
MCH 3COOH= MNaOH X V NaOH
VCH 3COOH
MCH 3COOH = 0.5 X 15.2
20
= 0.38 mol/L
Strength of acetic acid = 0.38 X 60 g/L
= 22.8 g/L
EXPERIMENT 2
Take the household vinegar in the conical flask and do the
titration with NaOH as mentioned
OBSERVATIONS:-
CALCULATIONS:-
We know that:-
MCH3COOH X V CH3COOH=M NaOH X V NaOH
MCH3COOH= MNaOH X V NaOH
VCH3COOH
MCH 3COOH = 0.5 X 13.5
10
= 0.675 mol/L
Strength of acetic acid = 0 .675 X 60
=40.5 g/L
EXPERIMENT 3
Take the wine vinegar in the conical flask and do the titration with NaOH as mentioned.
OBSERVATIONS:-
CALCULATIONS:-
We know that:-
MCH3COOH X V CH3COOH=M NaOH X V NaOH
MCH3COOH= MNaOH X V NaOH
VCH3COOH
MCH 3COOH = 0.5 X 24
10
= 1.2 mol/L
Strength of acetic acid = 1.2 X 60 g/L
= 72 g/L
RESULT
➢ Strength of acetic acid in laboratory vinegar = 22.8 g/L
➢ Strength of acetic acid in household vinegar = 40.5 g/L
➢ Strength of acetic acid in wine vinegar = 72 g/L
Graphically plotting various vinegar samples in accordance with the amount of acetic acid present in them we present a
stunning find :-
Order of amount of acetic acid in vinegar is:-
Wine Vinegar > Household Vinegar > Laboratory Vinegar
PRECAUTIONS
• Transfering of measured vinegar into a measuring
flask should be done very carefully .
• Measuring must be performed carefully.
• Look at the meniscus of solution at eye level to avoid
parallax.
• Look at the lower meniscus in the light coloured solution
and upper meniscus in the dark coloured solution because
of visibility.
• Do not forget to add distilled water to the vinegar.
BIBLIOGRAPHY
1. Comprehensive Lab Manual for Class XII by Laxmi
Publication.
2. www.icbse.com
3. www.google.com
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