A system at equilibrium is placed under stress by adding more reactant. If this reaction has a small equilibrium constant (Keq), how will the addition of this stress affect the equilibrium of this system?
I can't tell you the multiple choice answer, but that should not matter...
Recall that an equilibrium constant for the reaction
#aA + bB -> cC + dD#
#K_(eq) = ([C]^c[D]^d)/([A]^a[B]^b)#,
#a,b,c,d#are the stoichiometric coefficients of #A,B,C,D#, respectively, and #[" "]#indicates molar concentration.
If an equilibrium constant is small, i.e.
#K_(eq) < 1#,
then that means there are more reactants than products before the equilibrium is disturbed.
(Note that in principle, the actual size of
#K_(eq)#does not affect which direction the equilibrium shifts given a certain induced stress.)
Adding more reactants initially decreases the reaction quotient
That means it will shift to consume more reactants to generate more products.