Can some explain this using ice table?? Calculate #K_c# at this temperature. Provide your answer to two places after the decimal and without units.

At high temperatures, dinitrogen tetroxide gas decomposes into nitrogen dioxide gas. At #500^@ "C"#, a sealed vessel containing #"8.63 M"# of dinitrogen tetroxide gas was allowed to reach equilibrium. At equilibrium, the mixture contained #"3.65 M"# nitrogen dioxide gas.

1 Answer
Mar 2, 2018

I got #K_c = 1.96#.


The reaction was:

#"N"_2"O"_4(g) " "rightleftharpoons" " 2"NO"_2(g)#

#"I"" ""8.63 M"" "" "" "" ""0 M"#
#"C"" "-x" "" "" "" "+2x#
#"E"" "8.63-x" "" "" ""3.65 M"#

Note how the coefficients of each reactant go into the change in concentration... where else will you see them?

#K_c = (2x)^2/(8.63 - x)#

Now, we must already know #x#... But you would only know that once you write out the ICE table.

#x = 3.65/2 "M" = "1.83 M"#

Therefore,

#color(blue)(K_c) = ("3.65 M")^2/("8.63 M" - "1.83 M")#

#= color(blue)(1.96)#

Here the units are #"M"#, i.e. #"M"^2/"M" = "M"#, but we omit the units on purpose.