Experiment 1 Determination of the Acetic Acid Content of
Vinegar.
Pipette accurately, using a pipette filler,
10.00 cm3 of vinegar into a 100 cm3
volumetric flask, make up to the bottom of the stem using
distilled water, mix well then make up to the mark and mix again.
Rinse and fill your burette with this solution. Titrate a 10.00
cm3 (use a pipette filler ) aliquot
of the standard sodium hydroxide solution provided with
the vinegar solution, using phenolphthalein as
indicator.
Repeat the titration until two litres agree to within 0.1
cm3, i.e. you obtain concordant results. Be sure to
drain your pipette properly and to read your burette to two
decimal places (+/- 0.01 cm3). If there are any
doubts, ask your demonstrator.
Apparatus
25 cm3 or 50 cm3 beaker, 10 cm3
pipette, 100 cm3 volumetric flask, 100 cm3
beaker or conical flask, wash bottle, white tile, stand and
clamp.
Chemicals
15 cm3 of vinegar, 35 cm3 of standard
sodium hydroxide solution and phenolphthalein indicator.
Calculate:
(a) the molar concentration of acetic acid in the original sample
of vinegar.
(b) the mass of acetic acid per 100g of solution (the density of
acetic acid solution is 1.01 g/cm3 ).
Compare this value [from (b)] for the three different brand
names of vinegar provided. For each brand name use the average of
at least three (list them) values obtained from your classmates.
Complete your Lab. worksheet and submit
today.
Answer the following question on your worksheet.
1. What is the accuracy of the quantities measured using
(i) the pipette?
(ii) the burette?
(iii) the analytical balance?
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Lancashire,
The Department of Chemistry, University of the West Indies,
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Created Oct 2002. Links checked and/or last
modified 2nd April 2004.
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