A research team measures the rate of the reaction a total of five times

CHEMISTRY · Multi-part · A Level · Chemistry · Rate equations · Rate equations

Problem

A research team measures the rate of the reaction D+E→products\mathrm{D} + \mathrm{E} \rightarrow \text{products} (30 ∘C)(30\,^{\circ}\text{C}) a total of five times. Two trials are intended as replicates to assess reliability. The initial-rate results are collected in the table.
Trial[D]0 (M)[\mathrm{D}]_0\,(\text{M})[E]0 (M)[\mathrm{E}]_0\,(\text{M})Initial rate (M s−1)(\text{M}\,\text{s}^{-1})
10.100.102.50×10−52.50 \times 10^{-5}
20.200.109.80×10−59.80 \times 10^{-5}
30.100.205.10×10−55.10 \times 10^{-5}
40.200.202.10×10−42.10 \times 10^{-4}
50.100.103.80×10−53.80 \times 10^{-5}
Assume a rate expression of the form rate=k[D]r[E]s\text{rate} = k[\mathrm{D}]^r[\mathrm{E}]^s. (a) Using the data, determine the reaction order with respect to D and to E. Clearly indicate which trials you select for each comparison and justify how you dealt with the discrepancy between Trials 1 and 5. (b) Compute the numerical value and appropriate units of the rate constant kk, using an average initial rate for the duplicated concentration set. (c) Propose two plausible experimental sources of error that could account for the difference between Trials 1 and 5, and explain how each source would influence the measured initial rate. (d) Predict the initial rate for a new experiment conducted with [D]0=0.15 M[\mathrm{D}]_0 = 0.15\,\text{M} and [E]0=0.30 M[\mathrm{E}]_0 = 0.30\,\text{M}.

Related theory

Browse the problem library