Homework Problem 11.41

[Cobie_Allen_1H]

Hey guys! I had a question on the homework. I just got a little confused.

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 degrees Celsius. At equilibrium, 17.4mg 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) <---> 2NH3(g) + CO₂(g).

Thanks for the help!

[Hao 1I]

Start with the ICE chart and and convert the grams of CO2 to moles. Then knowing that there are 2 moles of NH3 for every one mole of CO2, moles of CO2 will be doubled for NH3. Be aware that NH4(NH2CO2) is a solid!

[Cobie_Allen_1H]

Thank you so much for the help! Really appreciate it!

[Angela_Pu_3C]

Why do we plug in 1.581x10-3? The x (or molar concentration of CO2) is 1.581M (resulting in Kc=1.58) so I'm not sure how/why we use 1.581x10-3 instead.