# Reaction Rates Explanation?

Experiments show that the following redox reaction is second-order overall:

NO2(g) + CO(g) --> NO(g) + CO2(g)

In the reaction, the initial [NO2] is twice the initial [CO]. What is the ratio of the initial rate to the rate at 50% completion?

In the solution they say: [NO2]i = 2[CO]i

and then at 50% completion they say: [CO] = 1/2[CO]i and [NO2] = 0.75[NO2]i

where they getting the 1/2 and 0.75 from?

Borek
Mentor
Stoichiometry?

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methods

how? can you show the math behind it?

I dont see how they can get .75 if its at 50% completion. Wouldnt that mean NO2 is at 1.5 and CO is at 1? But they cant be since NO2 is twice the initial CO

Borek
Mentor
the initial [NO2] is twice the initial [CO]

They react 1:1, if half of the CO reacted, how much NO2 was left?

Edit: note, that 1.5/2=0.75...

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