Chemistry 5070/31 — October/November 2018

Put Q into the burette.

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

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

Q is $0.105\text{ mol / dm}^3$ sulfuric acid.

Calculate the number of moles of sulfuric acid present in the average volume of Q.

moles of sulfuric acid in the average volume of Q = ______

Using your answer from (b) and the equation shown, calculate the number of moles of sodium hydroxide in the volume of P used in the titration.

$$2\text{NaOH} + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}$$

moles of sodium hydroxide in the volume of P used = ______

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

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

Using your answer from (d), calculate the mass, in g, of sodium hydroxide in $1.00\text{ dm}^3$ of P.
[$M_r$: NaOH, 40]

mass of sodium hydroxide in $1.00\text{ dm}^3$ of P = ______ $\text{g}$

Using your answer from (e), calculate the mass of water present in the $9.82\text{ g}$ of damp sodium hydroxide used to make P.

mass of water present in $9.82\text{ g}$ of damp sodium hydroxide = ______ $\text{g}$

Calculate the percentage by mass of water present in the damp sodium hydroxide used to make P.

percentage by mass of water = ______