The concentration of a potassium hydroxide solution can be found by titration using a standard solution of ethanedioic acid dihydrate.
Calculate the mass, in g, of solid ethanedioic acid dihydrate (Mr=126.0M_r = 126.0Mr=126.0) needed to prepare 250 cm3250\text{ cm}^3250 cm3 of 0.0600 mol dm−30.0600\text{ mol dm}^{-3}0.0600 mol dm−3 ethanedioic acid solution.
The mass of ethanedioic acid dihydrate from part (a) is dissolved in a beaker containing 100 cm3100\text{ cm}^3100 cm3 of distilled water. Describe how this solution is used to make 250 cm3250\text{ cm}^3250 cm3 of the 0.0600 mol dm−30.0600\text{ mol dm}^{-3}0.0600 mol dm−3 ethanedioic acid solution.
Before the first titration, the 25.0 cm325.0\text{ cm}^325.0 cm3 pipette is rinsed with a small volume of the 0.0600 mol dm−30.0600\text{ mol dm}^{-3}0.0600 mol dm−3 ethanedioic acid solution. State why it is good practice to rinse the pipette in this way.
Potassium hydroxide is added to the burette using a funnel. State why it is good practice to remove the funnel from the burette before the titration.
In a different experiment, 1.42 g1.42\text{ g}1.42 g of solid ethanedioic acid dihydrate is used to make 250 cm3250\text{ cm}^3250 cm3 of standard ethanedioic acid solution. 25.0 cm325.0\text{ cm}^325.0 cm3 of this ethanedioic acid solution reacts with exactly 22.85 cm322.85\text{ cm}^322.85 cm3 of potassium hydroxide solution. The equation for the reaction is:
H2C2O4(aq)+2KOH(aq)→K2C2O4(aq)+2H2O(l) \text{H}_2\text{C}_2\text{O}_4(\text{aq}) + 2\text{KOH}(\text{aq}) \rightarrow \text{K}_2\text{C}_2\text{O}_4(\text{aq}) + 2\text{H}_2\text{O}(\text{l}) H2C2O4(aq)+2KOH(aq)→K2C2O4(aq)+2H2O(l)Calculate the concentration of the potassium hydroxide solution. Give your answer to 3 significant figures.
The uncertainty in the 25.0 cm325.0\text{ cm}^325.0 cm3 of solution from the pipette is ±0.06 cm3\pm0.06\text{ cm}^3±0.06 cm3. The total uncertainty in the 22.85 cm322.85\text{ cm}^322.85 cm3 of solution from the burette is ±0.10 cm3\pm0.10\text{ cm}^3±0.10 cm3. Calculate the total percentage error in using the pipette and burette. Give your answer to 2 significant figures.
