Chemistry 5070/32 — May/June 2018

Put P into the burette.

Pipette a $25.0\text{ cm}^3$ (or $20.0\text{ cm}^3$) portion of Q into a flask and titrate with 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 P required was ______ $\text{cm}^3$.

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

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

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 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 P that are due to sulfuric acid.

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

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

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

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 P.

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