Question

A(aq) + B(aq) → 2C(aq)

If K_c = 3.4 x 10^-17, this indicates that .....

		At equilibrium there will be nearly equal amounts of reactant and product.
		At equilibrium there will be no product formed.
		At equilibrium there will be considerably more product than reactant.
		At equilibrium there will be considerably more reactant than product. Which of the following are true for all reactions that have achieved equilibrium?       -       A.       B.    The reaction has stopped occuring.       -       A.       B.    The rate at which the reactants are forming product is the same rate at which the products are converting to reactants.       -       A.       B.    The concentration of reactants and products are equal.       -       A.       B.    A majority of the reactants have been converted to products. A. True B. False

Answer 1

The given reaction is

A (aq) + B (aq) <-----------> 2 C (aq)

We can write equilibrium constant as Kc = [C]^2 / [A] [B]

the given value of Kc = 3.4 x 10^-17 , therefore we have

3.4 x 10^-17 = [C]^2/ [A] [B]

such a low value indicates that the denominator of above equation must be very large as compared to numerator.

Therefore we can say that the amount of reactants at equilibrium is much more than that of product.

The correct statement is "'At equilibrium there will be considerably more reactant than product.""

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True or False statements

The reaction has stopped occuring : False

At equilibrium the reaction is still occuring but now the rate at which forward reaction occurs is equal to rate at which reverse reaction occurs. Therefore as soon as products are formed, they get dissociated back into reactants. And that makes the overall reaction to reach the state of equilibrium

The rate at which the reactants are forming product is the same rate at which the products are converting to reactants. : True

The concentration of reactants and products are equal. : False

It is not necessary that concentration of reactants and products have to be equal at equilibrium. It is equal only when equilibrium constant Keq = 1 for that reaction.

A majority of the reactants have been converted to products. : False

It is not necessary that majority of reactants have to be converted to products.Because for reaction that have low value of equilibrium constant, like the one we have above, majority of reactants are still present and a very small quantity is converted to products.