The document discusses rates of reaction and reaction order. It provides examples of how to calculate average rates of reaction using concentration data over time. It also explains how to determine the rate law and reaction order of a reaction by analyzing rate data at different concentrations of reactants. The overall reaction order is found by adding the orders of each reactant. Higher concentrations of reactants increase the rate according to the rate law.

1. Week 2 Rates of Reaction:
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Rates of reaction: how long does it take for a
reaction to occur?
-measure rate of anything, quantity per time
-traveling miles per hour, eating cookies per minute, typing
words per minute
-In chemical reactions, quantity is measured as
concentration (molarity = moles/Liter)
-Rate is then Molarity per second

2. Week 2 Rates of Reaction:
Factors that influence rate of reaction:
1)State of reactants:
2)Temperature of reaction:
3)Concentration of a reaction:
4)Presence of a catalyst:
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3. Week 2
Rates of Reaction
Br2(aq) + HCOOH (aq) à 2Br-(aq) + 2H+(aq) + CO2(g)
The following reaction was studied and the
concentration of Br2 was tracked to determine
the rate of reaction. The following data was
collected:
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4. Week 2
Rates of Reaction
Br2(aq) + HCOOH (aq) à 2Br-(aq) + 2H+(aq) + CO2(g)
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Time (s) [Br2] (M)
0 0.01200
50 0.01010
100 0.00846
150 0.00710
200 0.00596
250 0.00500
300 0.00420
350 0.00353
400 0.00296
Average rate can be determined between any point in time
within the range of the data set:
Average rate = −
∆"#!
∆$
𝑜𝑟 𝑟𝑎𝑡𝑒 = −
"#! "#$%& % "#! #$#'#%&
$"#$%& % $#$#'#%&
For the equation used to determine the
average rate of Br2, why is there a negative
in front of the equation?
What should the units of rate be?

5. Week 2
Rates of Reaction
Br2(aq) + HCOOH (aq) à 2Br-(aq) + 2H+(aq) + CO2(g)
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Time (s) [Br2] (M)
0 0.01200
50 0.01010
100 0.00846
150 0.00710
200 0.00596
250 0.00500
300 0.00420
350 0.00353
400 0.00296
Average rate = −
∆"#!
∆$
𝑜𝑟 𝑟𝑎𝑡𝑒 = −
"#! "#$%& % "#! #$#'#%&
$"#$%& % $#$#'#%&
What is the rate of the reaction with respect
to Br2 for the first 100 seconds of the
reaction?
What is the rate of the reaction with respect
to Br2 between 100 to 200 seconds of the
reaction?

6. Week 2
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0.00000
0.00200
0.00400
0.00600
0.00800
0.01000
0.01200
0.01400
0 50 100 150 200 250 300 350 400 450
Concentration
of
Br
2
(M)
Time (s)
[Br2] vs time
Rates of Reaction
Br2(aq) + HCOOH (aq) à 2Br-(aq) + 2H+(aq) + CO2(g)
Time (s) [Br2] (M)
0 0.01200
50 0.01010
100 0.00846
150 0.00710
200 0.00596
250 0.00500
300 0.00420
350 0.00353
400 0.00296
Thinking about your answers
on the previous slide, how
do those rates compare?
Why might this be the case?

7. Week 2
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0.00000
0.00200
0.00400
0.00600
0.00800
0.01000
0.01200
0.01400
0 50 100 150 200 250 300 350 400 450
Concentration
of
Br
2
(M)
Time (s)
[Br2] vs time
Rates of Reaction
Br2(aq) + HCOOH (aq) à 2Br-(aq) + 2H+(aq) + CO2(g)
In class, we talked about average and
instantaneous rate. Average rate is over a longer
time frame. Instantaneous rate is similar to
average rate, but would be at one point in time
along the graph.
For example: if you drove from Syracuse to
Boston (312 miles) in 5 hours, your average rate
of travel was 62.4 miles/hour. Instantaneous rate
would be checking your speedometer at one
point in time to see you were going 72
miles/hour (at that one point in time)

8. Week 2
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Reaction Order:
-need to be determined experimentally
-used to create Rate Law
-Rate Law – the relationship between rate of
the reaction and the product of the
concentrations of reactants in the reaction
-the products never show up in the Rate Law!

9. Week 2
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Reaction Order:
You run a reaction several times to determine that the Rate Law is:
Rate = k [X]2[Y]1[Z]2
What is the reaction order with respect to
[X]:
[Y]:
[Z]:
What is the overall order of the reaction?

10. Week 2
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Reaction Order:
You collect the rate data for the following reaction:
A + B à C at 25 ℃
What is the Rate Law of this reaction?
What is the order of the reaction with respect to [A]? [B]?
[A] (M) [B] (M) Rate (M/s)
1.50 1.50 0.032
1.50 3.00 0.064
3.00 1.50 0.128

11. Week 2
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Reaction Order:
You collect the rate data for the following reaction:
X + Y à Z at 32 ℃
What is the Rate Law of this reaction?
What is the order of the reaction with respect to [X]? [Y]?
What does this mean for the rate of the reaction if [Y] was 10 M? Or 100 M?
[X] (M) [Y] (M) Rate (M/s)
0.80 0.220 0.215
3.2 0.220 0.860
0.80 0.440 0.215