1.541 ± 0.001 g of hydrated oxalic acid crystals were dissolved in distilled water. The solution was placed in a 250.0 ± 0.5 cm3 volumetric flask and the total volume made up to the mark with distilled water. After thoroughly mixing the contents, 25.00 ± 0.04 cm3 of this solution was pipetted into a conical flask. This required 24.90 ± 0.08 cm3 of 0.100 ± 0.001 mol dm3 sodium hydroxide solution to be neutralised completely.
The equation for the reaction is:
(COOH)2(aq) + 2NaOH(aq) ↓ (COONa)2(aq) + 2H2O(l)
- (a) Calculatethepercentageuncertaintyassociatedwith:
- (i) the mass of the oxalic acid.
- (ii) the solution in the volumetric flask.
- (iii) the volume in the pipette.
- (iv) the molarity of the sodium hydroxide solution.
- (v) the volume of sodium hydroxide solution used.
- (b) Calculatethetotalpercentageuncertaintyforthisexperiment.
- (c) Calculate the molar mass of the oxalic acid obtained from these experimental results to thecorrect number of significant figures and state the uncertainty.
- (d) Thecorrectliteraturevalueforthemolarmassoftheacidis126.06gmol-1.Calculatethepercentage error.
- (e) State any other assumptions which may have affected the accuracy of the result.