A student performs a titration to find the concentration of a solution of potassium hydroxide (KOH\text{KOH}KOH).
He uses this method:
State what the student should do while adding the acid, to make sure that the indicator changes colour permanently.
The table shows the student's titration results.
| Titration | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Volume of acid added in cm3\text{cm}^3cm3 | 24.60 | 23.85 | 24.05 | 23.95 |
Concordant results are volumes within 0.20 cm3 of each other.
Identify which results are concordant.
Use the concordant results to calculate the average (mean) volume of acid added.
The table shows the titration results of another student.
| Parameter | Value |
|---|---|
| Volume of potassium hydroxide used in cm3\text{cm}^3cm3 | 25.0 |
| Concentration of sulfuric acid in mol/dm3\text{mol/dm}^3mol/dm3 | 0.0600 |
| Average volume of sulfuric acid added from burette in cm3\text{cm}^3cm3 | 21.50 |
The equation for the reaction is:
H2SO4+2KOH→K2SO4+2H2O \text{H}_2\text{SO}_4 + 2\text{KOH} \rightarrow \text{K}_2\text{SO}_4 + 2\text{H}_2\text{O} H2SO4+2KOH→K2SO4+2H2OCalculate the amount, in moles, of H2SO4\text{H}_2\text{SO}_4H2SO4 in 21.50 cm3 of the sulfuric acid.
Calculate the amount, in moles, of KOH\text{KOH}KOH in the potassium hydroxide solution.
Calculate the concentration, in mol/dm3\text{mol/dm}^3mol/dm3, of the potassium hydroxide solution.
Describe how you could use the method of crystallisation to obtain a pure, dry sample of potassium sulfate from a dilute solution of potassium sulfate.
39 exam-style questions on Edexcel IGCSE Chemistry Acids, alkalis and titrations. Each one has a worked solution and a mark scheme showing where the marks go.