For the reaction "CO"(g) + "NH"_3(g) rightleftharpoons "HCONH"_2(g)CO(g)+NH3(g)HCONH2(g), if "3.00 atm"3.00 atm of "CO"CO and "1.40 atm"1.40 atm of "NH"_3NH3 were allowed to react in a closed container, then if K_p = 2.70Kp=2.70 at a certain temperature, what is P_(HCONH_2)PHCONH2 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.