A student carries out a titration to find the concentration of a solution of sulfuric acid (H2SO4\text{H}_2\text{SO}_4H2SO4).
She is given:
She uses this method to do the titration:
Name the piece of apparatus that the student should use to add the sulfuric acid solution in step 1.
What is the colour change of the phenolphthalein indicator in step 4?
Why is it better to use phenolphthalein indicator rather than universal indicator in this titration?
The student repeats the experiment four times to find the volume of KOH\text{KOH}KOH needed for neutralisation. The table shows her results:
| Trial | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Burette reading after adding potassium hydroxide solution (cm3\text{cm}^3cm3) | 23.15 | 22.65 | 22.80 | 22.45 |
| Burette reading before adding potassium hydroxide solution (cm3\text{cm}^3cm3) | 0.40 | 0.50 | 0.60 | 0.35 |
| Volume of potassium hydroxide solution added (cm3\text{cm}^3cm3) | 22.75 | 22.15 | 22.20 | 22.10 |
The average (mean) volume of potassium hydroxide solution should be calculated using only concordant results. Concordant results are those volumes that differ from each other by 0.20 cm30.20\text{ cm}^30.20 cm3 or less.
Calculate the average volume of potassium hydroxide solution added.
In a different experiment under identical conditions, the student records the following titration results with another sample of sulfuric acid:
The equation for the reaction is:
2KOH+H2SO4→K2SO4+2H2O 2\text{KOH} + \text{H}_2\text{SO}_4 \rightarrow \text{K}_2\text{SO}_4 + 2\text{H}_2\text{O} 2KOH+H2SO4→K2SO4+2H2O(i) Calculate the amount, in moles, of KOH\text{KOH}KOH in 24.00 cm324.00\text{ cm}^324.00 cm3 of the potassium hydroxide solution.
(ii) Calculate the amount, in moles, of H2SO4\text{H}_2\text{SO}_4H2SO4 in the sulfuric acid solution.
(iii) Calculate the concentration, in mol/dm3\text{mol/dm}^3mol/dm3, of the sulfuric acid.
