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rate of reaction questions

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Offline allakk

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rate of reaction questions
« on: November 05, 2010, 05:25:44 PM »
Can someone please help me on these 2 questions? Thanks.

1. For the reaction 2A+ 2B -> 3C, it was found that the rate of disappearance of B was 0.3 mol L^-1 s^-1. What was the rate of disappearance of A and the rate of appearance of C?

2. At a certain temperature, the rate of decomposition of N2O5, 2N2O5-> 4NO2 +O2, is 2.5 x 10^-6 mol L^-1 s^-1. How fast are NO2 and O2 being formed?

Offline _rob

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Re: rate of reaction questions
« Reply #1 on: November 06, 2010, 05:48:56 PM »
Lets assume we are dealing with 1L so I dont need to keep writing moles per L per Second...

I havent come across this before, but would assume that because the ratio of A and B reacting is 1:1, that if 0.3 moles of A dissapear every second, then 0.3 moles of B must dissapear every second also.

2 moles of B and A react to form 3 moles of C, so the ratio is 2:3, or 1:1.5, therefore if 0.3 moles of the reactants dissapear every second, then 0.45 moles of C will appear.

Does this seem logical?

Rob

Offline rabolisk

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Re: rate of reaction questions
« Reply #2 on: November 06, 2010, 08:20:21 PM »
You are correct, but I think you should have forced him to think more than just provide him with answers, even though you did provide descriptions.

Offline Grundalizer

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Re: rate of reaction questions
« Reply #3 on: November 06, 2010, 09:24:39 PM »
Most people coming here don't want to be forced to think they just want answers.

Offline Borek

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Re: rate of reaction questions
« Reply #4 on: November 07, 2010, 03:47:24 AM »
Most people coming here don't want to be forced to think they just want answers.

Have you read forum rules?

If someone is too lazy to think it is their problem, not ours.
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Offline Grundalizer

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Re: rate of reaction questions
« Reply #5 on: November 07, 2010, 07:09:30 AM »
lol so you guys - points me..too hilarious

Offline _rob

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Re: rate of reaction questions
« Reply #6 on: November 07, 2010, 08:16:44 AM »
Thats a fair point about making him think, but to be honest, I didnt know the answer myself! I just read the question and explained how I would go about doing it from a logical point of view.
But yeh next time Ill just give pointers :)

Offline chsteven

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Re: rate of reaction questions
« Reply #7 on: November 08, 2010, 09:21:31 PM »
Lets assume we are dealing with 1L so I dont need to keep writing moles per L per Second...

I havent come across this before, but would assume that because the ratio of A and B reacting is 1:1, that if 0.3 moles of A dissapear every second, then 0.3 moles of B must dissapear every second also.

2 moles of B and A react to form 3 moles of C, so the ratio is 2:3, or 1:1.5, therefore if 0.3 moles of the reactants dissapear every second, then 0.45 moles of C will appear.

Does this seem logical?

Rob

Thanks, I had the same problem but now I know what to do.

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