Chemistry 5070/31 — May/June 2022

Put P into the burette.

Pipette $25.0\text{ cm}^3$ of Q into a flask and titrate with P, using methyl orange indicator.

Record your results in the table, repeating the titration as many times as you consider necessary to achieve consistent results.

Results

Burette readings

Summary

Tick (✓) the best titration results.

Using the best titration results the average volume of P required is ______ $\text{cm}^3$.

Q is $0.275\text{ mol / dm}^3$ sodium carbonate.

The ionic equation for the reaction is shown.

$$\text{CO}_3^{2-} + 2\text{H}^+ \rightarrow \text{H}_2\text{O} + \text{CO}_2$$

Use your results from (a) to calculate the concentration, in $\text{mol / dm}^3$, of hydrogen ions in P.

Give your answer to three significant figures.

______ $\text{mol / dm}^3$

P is a mixture of dilute hydrochloric acid, $\text{HCl}$, and dilute sulfuric acid, $\text{H}_2\text{SO}_4$.

The concentration of hydrochloric acid in P is $0.135\text{ mol / dm}^3$.

Use your answer from (b) to calculate the number of moles of hydrogen ions from sulfuric acid in $1.00\text{ dm}^3$ of P.

______ $\text{mol}$

Use your answer from (c) to calculate the concentration, in $\text{mol / dm}^3$, of sulfuric acid in P.

______ $\text{mol / dm}^3$

P is a mixture of equal volumes of dilute hydrochloric acid, $\text{HCl}$, and dilute sulfuric acid, $\text{H}_2\text{SO}_4$.

Calculate the concentration, in $\text{mol / dm}^3$, of the dilute hydrochloric acid used to make P.

______ $\text{mol / dm}^3$

Write the formulae of the two salts formed during this titration.

______ and ______