This question is about measuring and explaining rates of reaction.
A student investigates the rate of reaction when solid calcium carbonate (CaCO3\text{CaCO}_3CaCO3) reacts with an excess of dilute hydrochloric acid (HCl\text{HCl}HCl). To do this, the reaction is carried out in a conical flask, and the volume of carbon dioxide (CO2\text{CO}_2CO2) gas produced is collected and measured over time.
Suggest a reason why using a gas syringe to collect the gas instead of collecting it over water by downward displacement would give more accurate results in this experiment.
Figure 1 shows the results of this experiment when 50.0 cm350.0\text{ cm}^350.0 cm3 of a 0.15 mol dm−30.15\text{ mol dm}^{-3}0.15 mol dm−3 solution of hydrochloric acid reacts with an excess of calcium carbonate at 20∘C20^\circ\text{C}20∘C.
Use Figure 1 to calculate the rate of reaction at 1.0 minute1.0\text{ minute}1.0 minute. Deduce the units of your calculated rate.
The student repeats the experiment using the same volume and concentration of hydrochloric acid and the same mass of excess calcium carbonate, but at a temperature of 40∘C40^\circ\text{C}40∘C.
Describe how the curve for the reaction at 40∘C40^\circ\text{C}40∘C would compare to the curve at 20∘C20^\circ\text{C}20∘C shown in Figure 1.
Explain, in terms of collision theory and the Maxwell-Boltzmann distribution, why increasing the temperature from 20∘C20^\circ\text{C}20∘C to 40∘C40^\circ\text{C}40∘C increases the rate of reaction.