Chemistry Investigatory Project

2014Chemistry Investigatory Project

CONTENTS

1. Certificate2. Acknowledgement3. Introduction4. Theory5. Experimental Procedure6. Activity Experiment 1 Experiment 2 Experiment 37. Bibliography 8. Results9. Precautions

Certificate

This is to certify that _______________________ of Class XII has satisfactorily completed his chemistry investigatory project as prescribed by the AISSC course during the academic year 201X-201X.

Teacher in chargeDate:

Internal Examiner External Examiner

Acknowledgement

I would like to sincerely and profusely thank my chemistry teacher,PGT (Chemistry), for his able guidance and support in completing my project.

I would also like to extend my gratitude to the Principal for providing me with all the facility that was required.

Last but not the least; I would extend my gratitude towards all teaching and non teaching staff of School and towards my friends who has supported me to complete this project.

_______________________________

Aim of the project: Measuring the Amount of Acetic Acid in Vinegar by Titration with an Indicator solution

Summary: The accidental discovery in ancient times that grape juice, left undisturbed, turns into wine was a cause for celebration. Wine has been used in celebrations ever since. The subsequent and inevitable discovery that wine, left undisturbed, eventually turns into vinegar was not heralded with as much enthusiasm. However, over many long years the wonders of vinegar have been revealed, and will continue to be for many years to come.Ancients very quickly uncovered the tremendous versatility of vinegar. While records were not kept before 5000 BC legend has it that the Sumerians, a civilization of ancient Babylonia, used vinegar as a cleaning agent. The Babylonians discovered that vinegar slows or stops the action of bacteria that spoils food so they used it as a preservative. They also used it as a condiment. Caesar's armies used vinegar as a beverage. The Egyptian queen, Cleopatra, demonstrated its solvency powers by dissolving precious pearls in vinegar to win a wager that she could consume a fortune in a single meal. Helen of Troy apparently bathed in vinegar to relax. Hannibal, the famous African General, used vinegar to help his army cross the Alps. According to the writings of Titus Livius, a historian who lived around the time of Christ, obstructive boulders were heated and drenched in vinegar.2 This action cracked the boulders into small pieces, allowing them to be easily moved away.Vinegar has been revered throughout the ages. There are many Biblical references in both the Old and New Testaments that reveal the use of vinegar as a beverage, likely diluted and sweetened. In fact, the scriptures say that Jesus drank vinegar just before he was crucified. There are also Biblical references to the use of vinegar as a condiment to dip bread and as a remedy for infections and wounds. Vinegar is also mentioned in the Talmud where it is called for to make haroseth in Pesachim. Vinegar became one of our first medicines around 400 BC. Hippocrates, a Greek physician and writer, known as the father of medicine, extolled vinegar's therapeutic qualities. He prescribed drinking vinegar to his patients for many ailments.Vinegar came to the rescue in the Middle Ages in some extraordinary ways. During the Black Plague in Europe, thieves poured vinegar over their skin to protect themselves from germs before robbing the dead.3 During the seventeenth century in Europe and England vinegar was used as a deodorizer. Citizens held sponges soaked in vinegar to their noses to reduce the smell of raw sewage in the streets. Women conveniently carried vinegar-laden sponges in small silver boxes and men stored them in their walking canes. The powerful British Navy used vinegar to preserve food during long sea voyages and to clean the decks of their ships.4In modern times vinegar continues to play a valuable role in society. During World War I vinegar was used to treat wounds on the battlefields. Today, white vinegar is recommended for the treatment of rashes, bites and other minor ailments when camping. Vinegar has become most popular, however, as a condiment on French fries and as an ingredient in food and baking. The virtues of specialty vinegars, such as balsamic and rice vinegars are proclaimed with increasing passion by food connoisseurs. Vinegar is still used for pickling and preserving, but less so, as people have less time for this fine craft.

ObjectiveThe goal of this project is to determine the amount of Acetic Acid in different types of vinegar using titration with a colored pH indicator to determine the endpoint.

Introduction About VinegarVinegar is a liquid consisting mainly ofacetic acid (CH3COOH) andwater. The acetic acid is produced by thefermentationofethanolbyacetic acid bacteria. Vinegar is now mainly used as a cooking ingredient, but historically, as the most easily available mildacid, it had a great variety of industrial, medical, and domestic uses, some of which (such as a general household cleanser) are still promoted today.Commercial vinegar is produced either by fast or slow fermentation processes. In general, slow methods are used with traditional vinegars, and fermentation proceeds slowly over the course of months or a year. The longer fermentation period allows for the accumulation of a nontoxic slime composed of acetic acid bacteria. Fast methods add mother of vinegar (i.e.,bacterial culture) to the source liquid before adding air using aventuri pumpsystem or aturbineto promote oxygenation to obtain the fastest fermentation. In fast production processes, vinegar may be produced in a period ranging from 20 hours to three days. With those fast processes, commercial vinegar contains residual alcohol (about 6 to 7%). About phenolphthalein:Phenolphthaleinis a chemical compoundwith theformula C20H14O4and is often written as "HIn" or "phph" in shorthand notation. Often used in titrations, it turns colorless inacidic solutions and pink inbasicsolutions. If the concentration of indicator is particularly strong, it can appear purple. In strongly basic solutions, phenolphthalein's pink color undergoes a rather slow fading reaction and becomes completely colorless above 13.0 pH.

Titration introduction:

In order to determine the concentration of a solution, there must be something to compare it against (benchmark). This benchmark is referred to as a standard. Sodium hydroxide (basic) is typically used as a standard to determine the concentration of acids. When an acid and base react, they form salt and water (neutral).

Acid + Base Salt + Water

A titration measures the volume of a solution added to a reaction using a burette. A burette is a long tube that is typically calibrated in millilitres. The acid and base are reacted together until one of the two is completely reacted. That point is called the endpoint which is neutral. If any additional acid or base is added, the solution will then become acidic or basic depending on which was added in excess. To visually determine the endpoint, an indicator is added to the reaction. An indicator is a chemical that changes colours at a particular pH. Since an acid base reaction upon completion is neutral, an indicator is used to visually indicate the point at which just a tiny excess of the acid or base is added beyond the completion of the reaction. In order to use a standardized solution, the solution must be prepared. After preparation, the exact concentration of the standard solution will be known. In this experiment, a standardized sodium hydroxide solution (NaOH) will be used. Using basic stoichiometry, the moles of acetic acid (CH3COOH) in the vinegar solution can be determined from the moles of NaOH added to the reaction.

APPARATUS REQUIRED FOR TRIATION:

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 OF TITRATION

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 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 NaOHStrength of acid in vinegar can be determined by the followingFormula:

Strength of acetic acid = MCH3COOH X 60Indicator: - PhenolphthaleinEnd Point: - Colorless to pink.

PROCESS OF TRITATION:

1. Clean a 50 ml burette and rinse with DI water. A clean burette will have no droplets clinging to the Inside of the glass. 2. Rinse the burette with two 5 ml portions of the Standardized NaOH solution. Make sure you drain the NaOH solution through the tip of the burette. 3. Using a funnel, fill the burette with the standardized NaOH solution. Make sure that the tip is also filled and there are no air bubbles in the tip. 4. Slowly drain the NaOH out of the burette until the burette reads 0.0 ml. Read from the bottom of the meniscus. It is sometimes helpful to hold a Piece of paper with a black line behind the burette and line it up with the meniscus. PREPARATION OF THE VINEGAR SOLUTION 5. Pipette 5 ml of the vinegar solution into a clean 250 ml flask. 6. Add 50 ml of DI water to the flask. 7. Add two drops of phenolphthalein indicator. DETERMINATION OF % ACETIC ACID IN A VINEGAR SOLUTION 8. Place a white background underneath the flask with the Vinegar solution. 9. Slowly add with constant swirling the NaOH drop-wise to the vinegar solution. 10. Continue adding drop wise to the vinegar solution until The vinegar solution turns a faint shade of pink that Remains for 30 seconds. This is called your endpoint. 11. Calculate the % by mass acetic acid in the vinegar solution.

Experiment 1:

Taking the laboratory vinegar in the conical flask and do the titration with NaOH as mentioned.

Observation: Sr.No.Volume of Vinegar Solution (in ml)Burette ReadingBurette ReadingVolume of NaOH solution used in (in ml)

120015.215.2

220015.215.2

320015.215.2

CONCORDATE VOLUME: 15.2 ml

CALCULATIONS:-We know that:-M CH3COOH X V CH3COOH = M NaOH X V NaOH

MCH 3COOH = M NaOH 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:

Taking the household vinegar in the conical flask and do the titration with NaOH as mentioned.Observation: Sr.No.Volume of Vinegar Solution (in ml)Burette ReadingBurette ReadingVolume of NaOH solution used in (in ml)

110013.213.5

210013.213.5

310013.213.5

CONCORDATE VOLUME: 13.5 mlCALCULATIONS:-We know that:-M CH3COOH X V CH3COOH = M NaOH X V NaOH

MCH 3COOH = M NaOH X V NaOH VCH 3COOH

MCH 3COOH = 0.5 X 13.2 10 = 0.38 mol/L

Strength of acetic acid = 0.675 X 60 g/L = 40.5 g/L

Experiment 3:

Taking the Wine vinegar in the conical flask and do the titration with NaOH as mentioned.

Observation: Sr.No.Volume of Vinegar Solution (in ml)Burette ReadingBurette ReadingVolume of NaOH solution used in (in ml)

11002424

21002424

31002424

CONCORDATE VOLUME: 24 mlCALCULATIONS:-We know that:-M CH3COOH X V CH3COOH = M NaOH X V NaOH

MCH 3COOH = M NaOH X V NaOH VCH 3COOH

MCH 3COOH = 0.5 X 24 10 = 1.2 mol/L

Strength of acetic acid = 1.2 X 60 g/L= 72 g/L

Results:

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

Order of amount of acetic acid in vinegar is:-

Wine Vinegar > Household Vinegar > Laboratory Vinegar

Precautions to be taken while titrating:

Usually an air bubble is present in the nozzle of the burette; it must removed before taking the initial reading. There should not be any leakage from the burette during titration. Keep your eye in level with the liquid surface while taking the burette reading or while reading the pipette or measuring flask etc. Always read lower meniscus in case of colorless solution and upper meniscus in case of colored solutions. Do not blow through the pipette tp expel the last drop of solution from it, simply touch the inner surface of the titration flask with the nozzle of the pipette for this purpose. Shaking of the titration flask should be continuous during adding the solution from the burette. Use your index finger while pipetting the solution. Do not waste your time in bringing the burette reading to zero before each titration.

Bibliography1. Website www.wikipedia.org www.google.com www.yahoo.com

2. BOOKS: Comprehensive Practical Manual Pradeeps New Course Chemistry Dinesh Companion Chemistry for Class 12 NCERT Class XII