A student is asked to design a quantitative investigation of how particle size affects the rate of reaction between solid calcium carbonate and aqueous hydrochloric acid. Equal masses of CaCO₃ in three different particle-size ranges (large chips, small granules, and fine powder) are available, along with standard laboratory equipment and 1.0 M HCl.
Design and analysis questions follow.
(a) Identify the independent variable, dependent variable, and two controlled variables for the investigation.
(b) Outline an experimental procedure that would allow the student to collect data suitable for determining initial reaction rates for each particle size. Include specific details about measurements and how frequently data should be recorded.
(c) Describe how the student could use the collected data to construct a graph that quantitatively compares the initial rates for the three samples. Explain what features of the graph would be analyzed to obtain those rates.
(d) Discuss two potential sources of experimental error specific to this investigation and explain how each could affect the calculated reaction rates.