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# Orders and rate Equations watch

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1. Hey,

There's question in my OCR textbook (p117, Q3 if anyone has it) and I'm not sure how they got to the final answer of
Spoiler:
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8.3 x 104 dm6 mol-2s-1

Here's the question:

The reaction between ozone and ethene has the following rate equation:
rate = k[O3][C2H4]

5.0 x 10-8 mol dm-3 of ozone was reacted with 1.0 x 10-8 mol dm-3 of ethene. The initial rate of this reaction was 1.0 x 10-12 mol dm-3

Calculate k

My method:

k = 1.0 x 10-12 divided by 5.0 x 10-8 * 1.0 x 10-8

Giving: 2000 dm3mol-1s-1
2. (Original post by Woody.)
Hey,

There's question in my OCR textbook (p117, Q3 if anyone has it) and I'm not sure how they got to the final answer of
Spoiler:
Show
8.3 x 104 dm6 mol-2s-1

Here's the question:

The reaction between ozone and ethene has the following rate equation:
rate = k[O3][C2H4]

5.0 x 10-8 mol dm-3 of ozone was reacted with 1.0 x 10-8 mol dm-3 of ethene. The initial rate of this reaction was 1.0 x 10-12 mol dm-3

Calculate k

My method:

k = 1.0 x 10-12 divided by 5.0 x 10-8 * 1.0 x 10-8

Giving: 2000 dm3mol-1s-1
your unit of the rate constant is correct. I mean based on the rate equation you are given, the unit of the rate constant given in the actual answer is already wrong. unit of rate is dm-3mol1s-1
3. (Original post by shengoc)
your unit of the rate constant is correct. I mean based on the rate equation you are given, the unit of the rate constant given in the actual answer is already wrong. unit of rate is dm-3mol1s-1
it is mol dm-3 s-1 in the book,

although that has to be a major typo?? it is 2000 dm3 mol-1 s-1???
4. I also got 2000dm^3 mol^-1 s^-1
5. (Original post by LearningMath)
I also got 2000dm^3 mol^-1 s^-1
good times, i have found SOOOO many typos in this damn book
6. (Original post by JordanCarroll)
it is mol dm-3 s-1 in the book,

although that has to be a major typo?? it is 2000 dm3 mol-1 s-1???
I can't be bothered with the values, but based on the wrong unit the book gives, it is most likely the values are obtained wrongly, hence should be wrong as well.
7. yeh it sounds like a typo, you've worked it out right

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Updated: February 2, 2010
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