A student investigates the rate of reaction between magnesium ribbon and dilute hydrochloric acid.
The student collects and measures the volume of hydrogen gas produced in a gas syringe.
Which other piece of laboratory equipment and setup could the student use to collect and measure the volume of hydrogen gas?
The table shows the volume of hydrogen gas collected at 15-second intervals:
Time (s)Volume of hydrogen gas (cm3)00151830324543605175579061105631206413564 \begin{array}{|c|c|} \hline \text{Time (s)} & \text{Volume of hydrogen gas } (\text{cm}^3) \\ \hline 0 & 0 \\ 15 & 18 \\ 30 & 32 \\ 45 & 43 \\ 60 & 51 \\ 75 & 57 \\ 90 & 61 \\ 105 & 63 \\ 120 & 64 \\ 135 & 64 \\ \hline \end{array} Time (s)0153045607590105120135Volume of hydrogen gas (cm3)0183243515761636464State the time at which the reaction stops.
The student observes that some magnesium ribbon is still visible in the conical flask when the reaction stops. Explain why the reaction has stopped.
Another student reacts calcium carbonate with dilute nitric acid. The student performs two experiments using the same mass of calcium carbonate and the same volume of acid:
Experiment 1Experiment 2Calcium carbonate formlarge lumpsfine powderAcid concentration (mol/dm3)0.51.5Reaction time (s)24020 \begin{array}{|c|c|c|} \hline & \text{Experiment 1} & \text{Experiment 2} \\ \hline \text{Calcium carbonate form} & \text{large lumps} & \text{fine powder} \\ \hline \text{Acid concentration } (\text{mol/dm}^3) & 0.5 & 1.5 \\ \hline \text{Reaction time (s)} & 240 & 20 \\ \hline \end{array} Calcium carbonate formAcid concentration (mol/dm3)Reaction time (s)Experiment 1large lumps0.5240Experiment 2fine powder1.520Describe and explain, using the reacting particle model, the difference in the rate of reaction between the two experiments. Suggest how the experimental design could be improved.