Describe how to determine the theoretical temperature rise from a graph of temperature against time for a reaction involving sodium carbonate.

a) I cannot draw on the graph. You would need to plot your experimental data and then draw two best-fit straight lines: one for the initial temperature before adding sodium carbonate and another for the cooling of the solution after the reaction. Extrapolate these lines to $t = 2\frac{1}{2}$ minutes.

b) To find the theoretical temperature rise ($\Delta T$) at $t = 2\frac{1}{2}$ minutes, you would read the temperature from the extrapolated initial line at $t = 2\frac{1}{2}$ minutes and subtract it from the temperature read from the extrapolated cooling line at $t = 2\frac{1}{2}$ minutes. Since the graph