\({\text{50 c}}{{\text{m}}^{\text{3}}}\) of copper(II) sulfate solution is measured into a plastic cup using a \({\text{100 c}}{{\text{m}}^{\text{3}}}\) measuring cylinder. Excess zinc powder is added and the temperature rise that occurs is measured with a –10 °C to +110 °C thermometer. The enthalpy change for the reaction is then calculated. Which statement is correct?

A.     Systematic error will be reduced by repeating the experiment several times and averaging the results.

B.     Random error will be reduced by insulating the plastic cup.

C.     Random error will be reduced by using a 50 cm\(^3\) graduated pipette instead of a measuring cylinder.

D.     Systematic error will be increased by using a larger volume of copper(II) sulfate solution.

C

One respondent remarked that it was good to see a more demanding Q30. This was born out by the statistics where it appeared as the second hardest question on the paper. It is important that lab work breeds familiarity with errors, both random and systematic.