In a first-order reaction, the half-life of the reactant is 30 minutes. How long will it take for the concentration of the reactant to decrease to 12.5% of its initial value?
60 minutes
90 minutes
120 minutes
150 minutes
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The rate expression for the reaction between iodine and propanone is determined to be:
Rate = k [H+] [C3H6O]
Which graph is consistent with this information?
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1 markFor the reaction
C2H5Br (aq) + OH- (aq) → C2H5OH (aq) + Br - (aq)
the following data were collected at constant temperature:
[C2H5Br] / M | [OH-] / M | Rate / M s-1 |
|---|---|---|
3.0 x 10-3 | 2.0 x 10-2 | 4.0 x 10-4 |
6.0 x 10-3 | 2.0 x 10-2 | 8.0 x 10-4 |
6.0 x 10-3 | 4.0 x 10-2 | 1.6 x 10-3 |
What is the correct rate law for this reaction?
Rate = k [C2H5Br] [OH-]
Rate = k [C2H5Br] [OH-]2
Rate = k [C2H5Br]2 [OH-]
Rate = k [C2H5Br]2 [OH-]2
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1 mark2N2O5 (g) → 4NO2 (g) + O2 (g)
At high temperatures, N2O5 (g) decomposes according to the equation above. A sample of N2O5 (g) is monitored as it decomposes, and the concentration of N2O5 (g) as a function of time is recorded. The results are shown in the table below.
Time / s | [N2O5] / M |
|---|---|
0 | 0.850 |
60.0 | 0.654 |
120.0 | 0.532 |
180.0 | 0.448 |
What is the average rate of the reaction between 120.0 and 180.0 seconds?
7.0 x 10-4 M s-1
1.0 x 10-3 M s-1
1.4 x 10-3 M s-1
1.6 x 10-3 M s-1
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CaCO3 (g) + H2SO4 (aq) → CaSO4 (aq) + H2O (l) + CO2 (g)
The reaction between CaCO3 (s) and H2SO4 (aq) is represented by the equation above.
In a kinetics experiment, a 0.25 g sample of powdered CaCO3 (s) is added to a flask containing 50 mL of 1.5 M H2SO4 (aq) at 25 oC. The rate of the reaction is determined by measuring the volume of CO2 (g) produced over time.
Which of the following experimental changes is most likely to increase the rate of CO2 (g) production?
Using a 0.25 g sample of CaCO3 (s) chips instead of powdered CaCO3 (s).
Using 1.0 M H2SO4 (aq) instead of 1.5 M.
Using 100 mL of 1.5 M H2SO4 (aq) instead of 50 mL.
Warming the H2SO4 (aq) to 35 oC before its addition to the CaCO3 (s).
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1 markAn investigation into the rate of reaction between compounds A and B was performed.
A + B → C + D
The results from three different experiments carried out at a constant temperature were collected:
[A] / M | [B] / M | Rate / M s-1 |
0.30 | 0.50 | 6.0 x 10-4 |
0.30 | 0.25 | 1.5 x 10-4 |
0.60 | 0.25 | 3.0 x 10-4 |
The rate equation for this reaction is rate = k [A] [B]2
What is the value of the rate constant, k?
4.0 x 10-3
3.2 x 10-2
8.0 x 10-3
2.7 x 10-2
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1 markAmmonia decomposes into nitrogen gas and hydrogen gas, at high temperatures. A sample of ammonia is monitored as it decomposes, and the concentration of hydrogen is recorded over time. The results are shown in the table below.
Time / s | [H2] / M |
|---|---|
0 | 0.646 |
60.0 | 0.491 |
120.0 | 0.388 |
180.0 | 0.318 |
What is the average rate of the reaction between 60.0 and 120.0 seconds?
8.5 x 10-4 M s-1
5.7 x 10-4 M s-1
1.7 x 10-3 M s-1
5.2 x 10-3 M s-1
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1 markA first-order reaction has a half-life of 62 s. What fraction of reactant remains after 124 s?
1/2
1/4
1/8
1/16
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Which of the following statements about the integrated rate law for a first-order reaction is true?
The x-intercept of the ln[A] vs. t plot represents the half-life of the reaction.
The y-intercept of the ln[A] vs. t plot represents the initial concentration of A.
The slope of the ln[A] vs. t plot is equal to the rate constant k.
The area under the ln[A] vs. t plot represents the total amount of product formed.
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A rate law is found to be
Rate = k [A]2 [B]
Which of the following changes will not alter the initial rate of reaction?
Doubling the concentration of A and B
Doubling the concentration of A and halving the concentration of B
Halving the concentration of A and doubling the concentration of B
Halving the concentration of A and quadrupling the concentration of B
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For the general reaction V + W + X → Y + Z, the rate equation is:
rate = k [V] [W] [X]
What will happen to the rate of reaction when the concentration of all three reactants is doubled?
Increase by a factor of 2
Increase by a factor of 4
Increase by a factor of 6
Increase by a factor of 8
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