Question

Consider the reaction: NO2(g) + CO(g) ⇌ NO(g) + CO2(g) Kc = 0.30 at some temperature. If the initial mixture has the concentrations below, the system is_______.

Answer 1

This is an incomplete question, here is a complete question.

Consider the reaction: $NO_2(g)+CO(g)\rightleftharpoons NO(g)+CO_2(g)$

Kc = 0.30 at some temperature.

If the initial mixture has the concentrations below, the system is_______.

Chemicals   Concentration (mol/L)

- NO₂            0.024

- CO               0.360

- NO               0.180

- CO₂             0.120

Possible answers:

1) not at equilibrium and will remain in an unequilibrated state.

2) not at equilibrium and will shift to the left to achieve an equilibrium state.

3) not at equilibrium and will shift to the right to achieve an equilibrium state.

4) at equilibrium

Answer : The correct option is, (2) not at equilibrium and will shift to the left to achieve an equilibrium state.

Explanation:

Reaction quotient (Qc) : It is defined as the measurement of the relative amounts of products and reactants present during a reaction at a particular time.

First we have to determine the value of reaction quotient (Qc).

The given balanced chemical reaction is,

$NO_2(g)+CO(g)\rightleftharpoons NO(g)+CO_2(g)$

The expression for reaction quotient will be :

$Q_c=\frac{[NO][CO_2]}{[NO_2][CO]}$

In this expression, only gaseous or aqueous states are includes and pure liquid or solid states are omitted.

Now put all the given values in this expression, we get

$Q_c=\frac{(0.180)\times (0.120)}{(0.024)\times (0.360)}=2.5$

Equilibrium constant : It is defined as the equilibrium constant. It is defined as the ratio of concentration of products to the concentration of reactants.

There are 3 conditions:

When $Q>K$ that means product > reactant. So, the reaction is reactant favored.

When $Q$ that means reactant > product. So, the reaction is product favored.

When $Q=K$ that means product = reactant. So, the reaction is in equilibrium.

The given equilibrium constant value is, $K_c=0.30$

From the above we conclude that, the $Q>K$ that means reactant < product. So, the reaction is reactant favored that means reaction must shift to the reactant or left to be in equilibrium.

Hence, the correct option is, (2) not at equilibrium and will shift to the left to achieve an equilibrium state.