Use Table 2.1 to complete the three missing entries.
The parts of the thermometer used in Experiment $5$ are shown in Fig. 2.1. The liquid levels inside the thermometer are not shown. Finish Fig. 2.1 by drawing the liquid level to represent: • the initial temperature of $\textbf{P}$ in Experiment $5$ • the highest temperature reached in Experiment $5$.
Draw a graph of temperature rise against volume of $\textbf{Q}$ on the grid in Fig. 2.2. You should: • plot the point $(0,0)$ because there is no temperature rise when no $\textbf{Q}$ is added • plot the temperature rises and volumes of $\textbf{Q}$ from Table 2.1 • draw a straight line of best fit for the first four points • draw a straight line of best fit for the last three points • extend the lines so that they intersect.
The point where the two lines meet shows the volume of $\textbf{Q}$ that exactly neutralises $25.0\ \text{cm}^3$ of $\textbf{P}$. Determine the volume of $\textbf{Q}$ at the point where the two lines on the graph cross.
$\textbf{Q}$ is $2.24\ \text{mol}/\text{dm}^3$ hydrochloric acid. Use your answer to (d) to calculate the concentration of potassium hydroxide in $\textbf{P}$. $\text{KOH} + \text{HCl} \rightarrow \text{KCl} + \text{H}_2\text{O}$
A measuring cylinder is used to measure the volumes of water. Suggest why the volumes of water in Table 2.1 are not shown to one decimal place.
State and explain why a plastic cup is used instead of a metal cup in these experiments.
State why the mixture is stirred before the temperature is measured in these experiments.