Volumetric analysis
exercise 4 solution
|
Volume
|
Volume
|
Volume
|
|
| Start |
11.40
mls
|
21.43
mls
|
13.40
mls
|
| Finish |
22.22
mls
|
32.22
mls
|
22.22
mls
|
| Total |
10.82
mls
|
10.79
mls
|
8.82
mls
|
Average titre = (10.82
+ 10.79)/2=10.81mls
To calculate the average
titre take only the concordant results
Irene determines the amount of vitamin C in a 18 ml sample of fruit juice by titrating it against an 0.023M standard iodine solution. Three titres were obtained and the results are shown on the left. What is the concentration of vitamin C in the fruit juice?
The equation for the reaction is shown below.
Step 1 Calculate
the mole of substance delivered from the burette. In this case iodine
solution
Mole = Average Volume(litres)
X Concentration
Mole = 0.011 X 0.023 = 0.000253
Step 2 Using
the equation calculate the number of mole of substance in the 18 ml
aliquot. In this case vitamin C.
For every one mole of
iodine one mole of vitamin C reacts. Hence the number of mole of vitamin
C present is 0.000253.
Step 3 Find the concentration of the substance in theoriginal fruit juice. In this case find the concentration of vitamin C in the 18 ml sample of fruit juice.
The Concentration in the 18ml sample of fruit juice
= 0.00025/0.018 = 0.014M