## determine K

Ekayana Sethi 2K
Posts: 47
Joined: Wed Nov 16, 2016 3:03 am
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### determine K

For the first-order reaction A -->3 B +C, when [A]o is
0.015 mol!L"1 , the concentration of B increases to 0.018 mol!L"1
in 3.0 min. What is the rate constant for the reaction expressed
as the rate of loss of B?

sofiakavanaugh
Posts: 58
Joined: Thu Jul 13, 2017 3:00 am
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### Re: determine K

I think this is one were you first have to find [A]t. To do this you first write the increase in [B] in terms of [A], which means you need to multiply mol B/L x (1 mol A/3 mol B). Then you take your [A]o and subtract the number you just calculated from it. Since its first order, you use the integrated rate law ln[A]t=-kt + ln[A]o, plug in the number you just calculated for [A]t, your time is 3 min, and you also are given [A]o, and then rearrange the equation to get k. Note, make sure your units of k are correct, if they ask for it in seconds you may need to convert.

Hope this helps.

Ekayana Sethi 2K
Posts: 47
Joined: Wed Nov 16, 2016 3:03 am
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### Re: determine K

yes I know how to calculate in terms of A but what about in terms of B?

mayapartha_1D
Posts: 50
Joined: Fri Sep 29, 2017 7:07 am

### Re: determine K

Because there are 3 moles of B and only one of A it should be the same process just use the equation that would include 1/3!