is there any way to know if its products or reactants..?
The equilibrium constant for the gas phase reaction
N2 (g) + 3H2 (g) (2 arrows: one to right, one to left.) 2NH3 (g)
is Keq = 4.34 × 10^-3 at 300°C. At equilibrium, __________.
A) reactants predominate
B) only reactants are present
C) roughly equal amounts of products and reactants are present
D) only products are present
E) products predominate
yes.
Q = (NH3)^2/(N2)(H2)^3 = 4.34E-3
In general, A is true. For Q to be small, the numerator must be small and the denominator must be large. The only way you get that is for the products to be small and the reactants to be large(r).
It's easier to answer questions like this when the squared and cubed terms are missing (concns just to the first power) such as K = (A)/(B)(C); then only A would b true out of all of the possibilities given. B and D are never true. C is true, in the simpler K I mentioned above, when k = 1; it's tougher to work it out with the squared and cubed terms there. But you can make up a scenario where NH3 = 2 and (H2) + N2 = 2, then Q = 1/4 (1 for 1 of each, 1/4 for 2 of each, 1/9 for 3 of each, 1/16 for 4 of each etc BUT products are always decreasing with those numbers which still means products are less than reactants.
i understand a lot better now, thank you. someone tried to explain about k=1 and i just got more confused. thank you for taking the time to explain.
I have another question, if Keg was negative would it make a difference?
To determine whether products or reactants predominate at equilibrium, you need to compare the value of the equilibrium constant (Keq) to its magnitude. The equilibrium constant expresses the ratio of the concentrations (or pressures if the reaction involves gases) of the products to the concentrations (or pressures) of the reactants at equilibrium.
In this case, the equation is:
N2 (g) + 3H2 (g) ⇌ 2NH3 (g)
And the given value of Keq is 4.34 × 10^-3.
If the value of Keq is very small (close to zero), it means that the concentration or pressure of the products is much smaller compared to the reactants. Therefore, reactants "predominate" or are present in larger amounts at equilibrium. This corresponds to option A) "Reactants predominate".
Conversely, if Keq is very large (much greater than 1), it indicates that the concentration or pressure of the products is substantially greater than that of the reactants. Therefore, products "predominate" or are present in larger amounts at equilibrium.
In this case, since the given value of Keq (4.34 × 10^-3) is relatively small, reactants predominate at equilibrium.