Volumetric analysis
Calculations
|
Volume
|
Volume
|
Volume
|
|
| Start |
1.40
mls
|
11.40
mls
|
2.40
mls
|
| Finish |
22.22
mls
|
32.22
mls
|
22.22
mls
|
| Total |
20.82
mls
|
20.82
mls
|
19,82
mls
|
Average volume=(20.82 + 20.82)/2 = 20.82
The concordant results should be used to arrive at the average volume.
A 20 ml sample hydrochloric acid solution was titrated against a 0.05 M sodium carbonate solution. Three separate titres were obtained and the results are shown on the left.
Calculate the concentration of hydrochloric acid in the test sample.
The equation for the reaction is shown below.
Step 1 Calculate
the mole of substance delivered from the burette. In this case sodium
carbonate
Mole = Average Volume(litres)
X Concentration
Mole = 0.0208 X 0.05 = 0.00104 mole
Step 2 Using
the equation calculate the number of mole of substance in the test sample.
In this case HCl.
According to the equation
above for every mole of sodium carbonate 2 mole of HCl reacts. Hence
the mole of HCl = 0.00104 X 2 = 0.00208 mole
Step 3 Find
the concentration of the substance in the test sample. In this case
find the concentration of acid in the 20 ml sample.
Concentation = mole/volume(litres) = 0.00282 / 0.02 = 0.104M