Volume of alkali X concentration of alkali
Apparatus and Materials:
-
25 cm3 Pipette
-
10 cm3 Burette
- Retort stand
- Conical Flask
- Funnel
- 2 Beakers
- Marble
- Safety Glasses
- Distilled water
- Alkali
- Standard solution of acid phenolphthalein
Method:
- Pour the Standard solution of the acid into the beaker.
- Wash the conical flask using distilled water.
-
Use a pipette to pour 25 cm3 of the acid into the flask.
- Pour 5-7 drops of phenolphthalein into the conical flask.
- Pour the alkali into the other beaker.
- Wash the burette using distilled water and then the acid.
- Attach the burette to the stand and with the help of a funnel pour the alkali in the pipette.
- Place the conical flask on the marble placed at the base of the retort stand.
- Remove the funnel, and let the alkali flow into the conical flask till the solution turns neutral.(shake the solution inside the flask to ensure that phenolphthalein is mixed properly and to obtain a clear result.At regular intervals, clean the tip of the burette using distilled water to avoid any errors)
- Record the volume of the alkali required to neutralize the acid
- Repeat the experiment a number of times to obtain precision and accuracy.
Data Analysis:
Calculations:
Let the concentration of the alkali be ‘A’
0.1 x (10 x 6) = A x (10.3+10.2+10.1+10.3+10.2+10.2)
Therefore, A = 0.097 g/ dm3
Error:
Uncertainty in the measurement of the burette is ±0.05 cm3
Total uncertainty for burette = 6 (0.05)
= 0.3 cm3
% error for burette = (0.3 / 61.3)100
= ± 0.48 %
Uncertainty in the measurement of the pipette is ±0.01 cm3
Total uncertainty for pipette = 6 (0.01)
= 0.06 cm3
% error for pipette = (0.06 / 60)100
= ± 0.036 %
Inaccuracy of the electronic balance: ±0.01 grams
% error of the electronic balance = (0.01/ (2.04)) 100
= ±0.49%
Uncertainty in the volumetric flask: ±0.05 cm3
% error in the volumetric flask = (0.05 / (100)) 100
= ±0.05%
Hence the error in the concentration of the acid is ±0.54%
Therefore, the total error in the concentration of the alkali
= ± (0.48+0.036+0.49+0.54) %
= ± 1.546%
Error Analysis:
The possible reasons for the error are:
- The fluctuating temperatures in the area where the experiment was being conducted caused inaccuracy to the calculations.
- There could have been error of parallax while taking the volume of the liquid.
- I might have exceeded the neutral mark while adding the alkali to the solution.
Conclusion
-
The concentration of alkali was 0.097 g/ dm3
- There could have been an improvement in the result if certain random errors had not occurred.