Question

1. The overall order for the reaction, A+B→C, is 2. A student tests this by measuring the reaction rate at one concentration of A and B, then doubling both concentrations at the same time and re-measuring the rate, which quadrupled. The student concludes that the data support the hypothesis that the above rate law is rate=k[A][B]. Analyze this.

a. The data do support the hypothesis but each trial should be repeated.
b. The data contradict the hypothesis because the rate should have doubled, not quadrupled. ***
c. The data support the hypothesis but a trial holding one reactant constant is needed.
d. The data contradict the hypothesis but testing by changing a single reactant will verify the hypothesis.

2. Determine the overall reaction order for the reaction, A+B→2C using the table of data below:

Experiment Initial [A]/M Initial [B]/M Initial rate/M s-1
1 0.010 0.040 0.0031
2 0.010 0.020 0.0015
3 0.020 0.020 0.0032

a. 0
b. 1
c. 2
d. 3 ***

Answer 1

2. Here's a better version of the table.
1 | 0.010 | 0.040 | 0.0031
2 | 0.010 | 0.020 | 0.0015
3 | 0.020 | 0.020 | 0.0032

Answer 2

I don't believe either answer is correct. What is your rationale for each?

Answer 3

1. since the order of reaction was 2, I thought it would double.
2. I change my answer to option C. Is that correct?
T 1 & 2: 0.0031 / 0.0015 = k (0.010)^m (0.040)^n / k (0.010)^m (0.020)^n. N = 1
T 2 & 3: 0.0015 / 0.0032 = (0.010/ 0.020)^n. M= 1
m + n = 1 + 1 = 2

Answer 4

Yes, 2c is correct.
On question 1, if you double one reactant that will double the rate. True. But if you double BOTH that will double BOTH and 2 x 2 = 4. So could 1b be correct?