Header Ads

Latest Publications

Learn The Truth About How Much Do You Know About Titration Of Vinegar? In The Next 60 Seconds.


How Much Do You Know about Titration Of Vinegar?


Objectives:
The objectives of this laboratory are to determine the molarity and percentage by mass of acetic acid in vinegar.
Introduction:


Vinegar is a common household item containing the solution of acetic acid as well as some other chemicals in water.The concentration of acetic acid may be expressed in molarity (mol/L) or as a mass percent,where
Molarity=Moles of acetic acid /volume of vinegar (in L)
Mass%=[mass of acetic acid/mass of vinegar]´100 in this technique a technique known as titration is used to determine the concentration of acetic acid in vinegar A titration involves performing a controlled reaction between a solution of known concentration (the titrant) and a solution of unknown concentration (the analyte).
Here the titrant is an aqueous solution of 0.1 M(0.2/0.5or 1) Sodium hydroxide(NaoH) and the analyte is vinegar When mixed a neutralization reaction occurs between sodium hydroxide and the acetic acid in vinegar.
NaOH(aq)+HC2 H 3O2  (aq) ®NaC2H3 O2 +H2O
The sodium hydroxide will be gradually added ti the vinegar in small amounts from a burette .A burette is such a device which allows the precise delivery of a specific volume of a solution. The NaOH will be added to the vinegar sample until all the acetic acid in the vinegar has been exactly consumed or reacted.At this point the reaction is completed and no more NaOH is needed.This is called equivalence point of titration.


In order to know that at which point equivalence point of titration is reached an indicator solution called as phenolphthalein is added to the vinegar at the beginning of the titration. phenolphthalein is   a pH sensitive organic dye .  phenolphthalein is colorless in acidic solutions like vinegar,and deep pink in acidic solution like Sodium hydroxide.
At the equivalence point of titration just one drop of NaOH will cause the entire solution in the Erlenmeyer flask to change from colorless to very pale  pink .
As the titration performed following data will be collected:
ð The Molarity of NaOH in aqueous form used,
ð The  volume of NaOH in aqueous form used to neutralized the vinegar ,
ð The volume of the vinegar used.

Using this data the molarity and mass percent of acetic acid in vinegar will be determined by performing a series of solution stoichometry calculations.
Procedure: 
Safety:
Be especially carefull in handling of the Sodium hydroxide base(NaOH) ,as it is corrosive and cause chemical burns to the skin.If any NaOH spills on you rinse it immediately under running water for up to 15 minutes.
Materials and equipment:
¤ Burette
¤ Volumetric pipette
¤ NaOH aqueous solution of 0.1 M(0.2/0.5or 1)
¤ Vinegar (any type including apple cider vinegar )
¤ Phenolphthalein
¤ Burette stand
¤ 250 ml(or 125ml)Erlenmeyer flask
Titration procedure:
Æ Rinse inside of the burette with distilled water. Allow the distilled water to drain out through the tip in order to ensure that the tip is also rinsed .
Æ Now rinse the burette with a small amount of NaOH in aqueous form.To do this add about 5-ml of NaOH to the burette then twirl the burette on it’s side to rinse it’s entire inner surface.Than allow the NaOH to drain out through it’s tip.
Æ Fill the burretee with NaOH up to the top,between the range of 0-ml to 5-ml.use a funnel to do this carefully,below the eye level,and preferabely over the sink.Now read the initial burette reading.
Æ The volumetric pipette is designed to measure and transfer exactly 5.00 ml of solution .First rinse the inside of the volumetric pipette with distilled water.
NaOH(aq)+HC2 H 3O2  (aq) ®NaC2H3 O2 +H2O
From equation one mole of NaOH will react with one mole of acetic acid.
So,
Z moles of NaOH = Z moles of acetic acid
Convert moles of acetic acid to one mole of acetic acid:
Gram moles of acetic acid =Z moles of acetic acid (formula mass of acetic acid/1 mole)
                                           = Z moles of acetic acid (60.1/1 mole)
                                              = k grams
Calculate percentage (%) by mass of acetic acid in vinegar:
% mass= Mass of acetic acid /Mass of vinegar
M=d.v assume that the density of vinegar is same as in water 1g/ml
So,
Mass of vinegar =density of the vinegar solution ´ volume of the vinegar solution
By putting the values in equation
1´ 5ml of the vinegar
=5g of the vinegar
Put the value in equation
%mass=mass of the acetic acid /mass of the vinegar
=Kg/5g
=-------------- %
Result:
From the above calculations it is concluded that -------------- % of acetic acid is present in vinegar.












No comments