A2 Chemistry rate of reaction and orders help

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username1482097
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#1
Report Thread starter 7 years ago
#1
Rate equation of this reaction is: rate = k[B][C]2

The original rate of reaction is 6.5 (mol dm-3 s-1) what would the new rate be if B was doubled and C was tripled at the same time.

Thanks in advance.
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Kill3er
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#2
Report 7 years ago
#2
Well B is first order and C is second order.

Doubling B doubles the rate (*2)
Tripling C multiple the rate by 3^2 (*9)

So multiply the rate by 2 and then multiply the answer by 9.
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Don Pedro K.
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#3
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#3
(Original post by Kill3er)
Well B is first order and C is second order.

Doubling B doubles the rate (*2)
Tripling C multiple the rate by 3^2 (*9)

So multiply the rate by 2 and then multiply the answer by 9.
I just did this stuff today for the first time, but I agree with what Mr. Kill3er has said here except for one thing; surely the tripling the concentration of C would result in the rate increasing by 2^3 and the other way round? So multiply by 8 instead of 9? I may be wrong but this is what I thought...
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Kill3er
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#4
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#4
(Original post by Don Pedro K.)
I just did this stuff today for the first time, but I agree with what Mr. Kill3er has said here except for one thing; surely the tripling the concentration of C would result in the rate increasing by 2^3 and the other way round? So multiply by 8 instead of 9? I may be wrong but this is what I thought...
Second order is squaring. Just finished A2
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Don Pedro K.
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#5
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#5
(Original post by Kill3er)
Second order is squaring. Just finished A2
Ohh okay Thanks for the clarification! How did you find A2 chem? I'm with Edexcel and I found As relatively easy; the exams in particular (I think I got around 73/80 give or take a couple of marks on both papers).
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Kill3er
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#6
Report 7 years ago
#6
(Original post by Don Pedro K.)
Ohh okay Thanks for the clarification! How did you find A2 chem? I'm with Edexcel and I found As relatively easy; the exams in particular (I think I got around 73/80 give or take a couple of marks on both papers).
I'm with aqa. It wasn't too bad. Lots of colours to memorise for transition metals.
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