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Reaction Rates given no dependence of the rate on the concentration of the chemical reactant
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Rate Law: Zeroeth-Order Reaction
A → BRate Law:
Rate = k x [A]0
B appears at same rate that A disappears, but the rate is independent of the
concentration of A
Time (s) [A] [B] K 0.05 M/s
0 1.50 0.00
ReactionBegins:InitialConcentrationOf A is 1.50 M
0 5 10 15 20 25 30 35 400
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Concentration v Time
A rearranging to B
[A]
[B]
time
Co
nce
ntr
atio
n (
M)
In first second,0.05 molarReduction in [A]And 0.05 molarIncrease in [B]
Time [A] [B]
0 1.50 0.00
1 1.45 0.05
0 5 10 15 20 25 30 35 400
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Zeroeth Order Reaction
Rate = k[A]º
[A]
[B]
time (s)
[A] (
M)
In second second, rate isthe same because[A] has no effect on the rate
Time [A] [B]
0 1.50 0.00
1 1.45 0.05
2 1.40 0.10
0 5 10 15 20 25 30 35 400
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Zeroeth Order Reaction
[A]
[B]
time (s)
[A] (
M)
After 30 seconds it is easy to see the reaction is over.
0 5 10 15 20 25 30 35 400
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Zeroeth Order Reaction
[A]
[B]
time (s)
[A] (
M)
Time [A] [B]
0 1.50 0.00
5 1.25 0.25
10 1.00 0.50
15 0.75 0.75
20 0.50 1.00
25 0.25 1.25
30 0.00 1.50
A reaction rate study yielding a linear relationship between time and concentration indicates a zeroeth order reaction in the reactant. This is uncommon.
This is the effect of changing the rate constant to 0.01 M/s. The reaction is much slower but the concentration does not affect the rate.
Lower Rate Constant
0 5 10 15 20 25 30 35 400
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Zeroeth Order Reaction
[A]
[B]
time (s)
[A] (
M)
This is the effect of changing the rate constant to 0.10 M/s. The reaction is much faster. Still no concentration effect.
Higher Rate Constant
0 5 10 15 20 25 30 35 400
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Zeroeth Order Reaction
[A]
[B]
time (s)
[A] (
M)
