Chemistry 5070/31 — May/June 2018

Put $\mathbf{P}$ into the burette.

Pipette a $25.0\text{ cm}^3$ (or $20.0\text{ cm}^3$) portion of $\mathbf{Q}$ into a flask and titrate with $\mathbf{P}$, using the indicator provided.

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 $\mathbf{P}$ required was ______ $\text{cm}^3$.

Volume of $\mathbf{Q}$ used was ______ $\text{cm}^3$.

$\mathbf{Q}$ is $0.225\text{ mol / dm}^3$ sodium carbonate.

Using your results from (a), calculate the concentration, in $\text{mol / dm}^3$, of hydrogen ions in $\mathbf{P}$. Give your answer to three significant figures.

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

concentration of hydrogen ions in $\mathbf{P}$ = ______ $\text{mol / dm}^3$

$\mathbf{P}$ is a mixture of dilute nitric acid, $\text{HNO}_3$, and dilute sulfuric acid, $\text{H}_2\text{SO}_4$.

The concentration of nitric acid in $\mathbf{P}$ is $0.125\text{ mol / dm}^3$.

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

moles of hydrogen ions in $1.00\text{ dm}^3$ of $\mathbf{P}$ due to sulfuric acid = ______

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

concentration of sulfuric acid in $\mathbf{P}$ = ______ $\text{mol / dm}^3$

$\mathbf{P}$ was made by mixing equal volumes of the two dilute acids.

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

concentration of dilute nitric acid used to make $\mathbf{P}$ = ______ $\text{mol / dm}^3$