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Rate Law: Zeroeth-Order Reaction

AB
Rate Law:
0
Rate = k x [A]

B appears at same rate that A
disappears, but the rate is independent
of the concentration of A
0

[A]

[B]

1.50

0.00

Reaction
Begins:
Initial
Concentration
Of A is 1.50 M

K

0.05

M/s

Concentration v Time
A rearranging to B
1.6
1.4
Concentration (M)

Time (s)

1.2
[A]
[B]

1
0.8
0.6
0.4
0.2
0
0

5

10

15

20
time

25

30

35

40
Time

[A]

[B]

0

1.50

0.00

1

1.45

0.05
Zeroeth Order Reaction
Rate = k[A]尊
1.6
1.4
1.2
[A]
[B]

1
[A] (M)

In first second,
0.05 molar
Reduction in [A]
And 0.05 molar
Increase in [B]

0.8
0.6
0.4
0.2
0
0

5

10

15

20
time (s)

25

30

35

40
Time

[A]

[B]

0

1.50

0.00

1

1.45

0.05

2

1.40

0.10
Zeroeth Order Reaction
1.6
1.4
1.2
1
[A] (M)

In second
second, rate is
the same
because
[A] has no effect
on the rate

[A]
[B]

0.8
0.6
0.4
0.2
0
0

5

10

15

20
time (s)

25

30

35

40
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

0.00

1.6
1.4
1.2

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.

1
[A] (M)

30

Zeroeth Order Reaction

[A]
[B]

0.8
0.6
0.4
0.2
0
0

5

10

15

20

25

30

35

40

time (s)

After 30 seconds it is easy to
see the reaction is over.
Lower Rate Constant
Zeroeth Order Reaction
1.6
1.4
1.2

[A] (M)

1
[A]
[B]

0.8
0.6
0.4
0.2
0
0

5

10

15

20

25

30

35

40

time (s)

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.
Higher Rate Constant
Zeroeth Order Reaction
1.6
1.4
1.2

[A] (M)

1
[A]
[B]

0.8
0.6
0.4
0.2
0
0

5

10

15

20

25

30

35

40

time (s)

This is the effect of changing
the rate constant to 0.10 M/s.
The reaction is much faster.
Still no concentration effect.

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