Question

For the chemical equation SO 2 ( g ) + NO 2 ( g ) − ⇀ ↽ − SO 3 ( g ) + NO ( g ) the equilibrium constant at a certain temperature is 3.70 . At this temperature, calculate the number of moles of NO 2 ( g ) that must be added to 2.86 mol SO 2 ( g ) in order to form 1.30 mol SO 3 ( g ) at equilibrium.

Answer 1

Answer : The number of moles of $NO_2$ gas added must be, 1.59 moles.

Explanation :

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

The equilibrium expression for the reaction is determined by multiplying the concentrations of products and divided by the concentrations of the reactants and each concentration is raised to the power that is equal to the coefficient in the balanced reaction.

The given equilibrium reaction is,

                        $SO_2(g)+NO_2(g)\rightleftharpoons SO_3(g)+NO(g)$

Initial conc.    2.86               x             0          0

At eqm.       (2.86-1.30)    (x-1.30)     1.30     1.30

The expression of $K_{eq}$ will be,

$K_{eq}=\frac{[SO_3][NO]}{[SO_2]NO_2]}$

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

$3.70=\frac{(1.30)\times (1.30)}{(2.86-1.30)\times (x-1.30)}$

$x=1.59$

Thus, the number of moles of $NO_2$ gas added must be, 1.59 moles.