homework help

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josephyim1L
Posts: 61
Joined: Fri Sep 28, 2018 12:15 am

homework help

Postby josephyim1L » Thu Jan 17, 2019 1:45 pm

Can someone explain the following question to me:

11.41 A 25.0-g sample of ammonium carbamate, NH4(NH2CO2), was placed in an evacuated 0.250-L flask and kept at 25 C. At equilibrium, 17.4 mg of CO2 was present. What is the value of Kc for the decomposition of ammonium carbamate into ammonia and carbon dioxide? The reaction is NH4(NH2CO2)(s) - 2 NH3(g)+ CO2(g).

Lorena Zhang 4E
Posts: 63
Joined: Fri Sep 28, 2018 12:16 am

Re: homework help

Postby Lorena Zhang 4E » Thu Jan 17, 2019 1:54 pm

First of all, you should turn all the mass into concentration. Then you should set up an ICE table. The initial concentration of ammonium carbamate can be calculated, and we know at initial point, there's only ammonium carbamate in the flask. For the change of concentration, it should be -x, +2x, +x respectively for each compound in the reaction based on the balanced equation. Since we know how much CO2 is present at equilibrium, we can generate the value of x. Finally we can write down Kc equation in terms of x and then plug in the number to get the result.


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