AQA A LEVEL CHEMISTRY 7405/2 PAPER 2 ORGANIC AND PHYSICAL CHEMISTRY VERSION 1.0 FINAL QUESTION PAPERS & MERGED MARKING SCHEME | JUNE 2023

This question is about rates of reaction. Figure 1 shows apparatus used to measure the rate of reaction when an acid reacts with an excess of solid sodium hydrogencarbonate, NaHCO3 When different monoprotic organic acids are used, the rates at which gas escapes can be used to compare the strengths of the acids. A timer is started when the NaHCO3 is added to the acid and the mass of CO2 gas lost is recorded at regular intervals. (It is assumed that any change in mass is due to the loss of CO2) Figure 1 0 1 . 1 Suggest a reason why using a conical flask instead of a beaker would give more accurate results in this experiment. [1 mark]3 *03* Turn over ► IB/M/Jun23/7405/2 Do not write outside the Figure 2 shows the results of this experiment when 25.0 cm3 of a box 2.23 mol dm–3 solution of ethanoic acid reacts with an excess of NaHCO3 Figur