For the reaction #"CO"(g) + "NH"_3(g) rightleftharpoons "HCONH"_2(g)#, if #"3.00 atm"# of #"CO"# and #"1.40 atm"# of #"NH"_3# were allowed to react in a closed container, then if #K_p = 2.70# at a certain temperature, what is #P_(HCONH_2)# at equilibrium?

1 Answer

With everything in a gas phase, we can use the partial pressures as proxies for the molar concentrations.

Explanation:

Set up the ICE Table

#sf(" "" "" "" "" ""CO"" "" "" ""NH"_3" "rightleftharpoons" ""HCONH"_2)#

#sf"Initial"##sf(" "" "" "3.00" "" "" "1.40" "" "" "" "0.00)#
#sf"Change"##sf(" "" " -x " "" "" "-x" "" "" "" "+x)#
#sf"Equilibrium"##sf(" "3 - x " "" "1.4 - x" "" "" "" " x)#

Then put those into the equilibrium expression and solve for x.

#2.70 = x/((3-x)(1.4-x))#

'#x#' will be the desired #sf(HCONH_2)# partial pressure.
You can calculate the equilibrium concentrations of the other gases from it, if desired.