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# A2 kinetics help watch

1. I worked out that H2 is first order but i cant figure out how to work out the order with respect to NO.....

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2. (Original post by Ismail786)
I worked out that H2 is first order but i cant figure out how to work out the order with respect to NO.....

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To work out the H order you used eq1&2

Now to work out the NO order you use 1&3 or 2&3. You know how a change in [H] affects rate.
3. (Original post by TeachChemistry)
To work out the H order you used eq1&2

Now to work out the NO order you use 1&3 or 2&3. You know how a change in [H] affects rate.
Yeah but im fully confused because the rate of reaction decreases in exp2&3 and 1&3. Completely lost
4. Notice how the concentration of NO decreases as well?

Compare Reaction 2 and 3

By what factor does NO decrease by?

Taking into account the order of reaction of H2, by what factor does the rate of reaction decrease by?

If you answered those questions.. you should get it now
5. (Original post by Ismail786)
Yeah but im fully confused because the rate of reaction decreases in exp2&3 and 1&3. Completely lost

Yes it does decrease. But that's because the [NO] decreases, so that makes sense.

Let's look at 1&3

What happens to [H] in going from 3 to 1? Knowing what you do about order wrt H how would this affect rate?
6. (Original post by TeachChemistry)
Yes it does decrease. But that's because the [NO] decreases, so that makes sense.

Let's look at 1&3

What happens to [H] in going from 3 to 1? Knowing what you do about order wrt H how would this affect rate?
From 3 to 1 it decreases (divide by 3) and as its first order id expect the rate to also decrease (divide by 3)
7. (Original post by RMNDK)
Notice how the concentration of NO decreases as well?

Compare Reaction 2 and 3

By what factor does NO decrease by?

Taking into account the order of reaction of H2, by what factor does the rate of reaction decrease by?

If you answered those questions.. you should get it now
Well if it was just [H] id expect the rate to double to 18.0x10^-3.... Im lost after this part
8. (Original post by Ismail786)
From 3 to 1 it decreases (divide by 3) and as its first order id expect the rate to also decrease (divide by 3)
Correct. So if you were to add a fourth line to the original table with [H] as in eq1 and [NO] as in eq3 what would that line in the table look like?
9. (Original post by TeachChemistry)
Correct. So if you were to add a fourth line to the original table with [H] as in eq1 and [NO] as in eq3 what would that line in the table look like?
Why would i add an extra line for??
10. Look at Reaction 1 and 3.

The concentrations of H2 multiples by three.

You said first order.
So you would expect the rate of reaction to be (6*10^-3)*3 = 1.8*10^-2

BUT, it's not that. It's 0.5*10^-3.
It's been divided by 36.

Now... by how much has the concentration of NO been divided by from Reaction 1 to 3?

You really should get it by now...
11. (Original post by Ismail786)
Why would i add an extra line for??
12. Seriously this is not hard, its just ratio using tables
13. (Original post by RMNDK)
Look at Reaction 1 and 3.

The concentrations of H2 multiples by three.

You said first order.
So you would expect the rate of reaction to be (6*10^-3)*3 = 1.8*10^-2

BUT, it's not that. It's 0.5*10^-3.
It's been divided by 36.

Now... by how much has the concentration of NO been divided by from Reaction 1 to 3?

You really should get it by now...
By a factor of 6 and 6^2 is 36 so its second order, ive got it now cant thank you enough sir, i salute you.
14. No problem.

I didn't want to help you too much, self-discovery is great, but it looked like you needed it.
15. (Original post by RMNDK)
No problem.

I didn't want to help you too much, self-discovery is great, but it looked like you needed it.
You helped too much, IMO. I think the OP would have benefitted from a slower, coaching led discovery.

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