CSEC Chemistry Paper 3 January 2021 - Free CXC Past Paper with Answers

TABLE 1: TIME–TEMPERATURE DATA

Using the axes provided in Figure 1, on page 7, plot a graph of temperature against time using the data in Table 1. Draw a smooth curve through the points on the graph.

From your graph, calculate the change in temperature ($\Delta T$), for the reaction taking place in the experiment.

State whether the reaction is exothermic or endothermic.

Write a balanced equation for the reaction occurring in the experiment.

Calculate the number of moles of sulfuric acid in the $50 \text{ cm}^3$ of $0.5 \text{ mol dm}^{-3}$ sulfuric acid solution that was used in the reaction.

Determine the number of moles of water that was produced in the reaction.

The final solution has a mass ($m$) of $153 \text{ g}$ and a specific heat capacity ($c$) of $3.82 \text{ J g}^{-1} \text{ }^\circ\text{C}^{-1}$. Using your answer in (b) (ii), calculate the heat change ($E$) for the reaction, given that $E = mc\Delta T$.

Calculate the enthalpy change for the reaction.

Suggest TWO ways in which the experiment could have been affected if it was carried out using an uncovered glass beaker instead of a calorimeter.

State ONE precaution that should be taken when stirring the reaction mixture.