Consider the following system at equilibrium where delta H degree = 182 kJ, and
ID: 486597 • Letter: C
Question
Consider the following system at equilibrium where delta H degree = 182 kJ, and K_c = 7.00 times 10^-5, at 673 K. NH_4I(s) NH_3(g) + HI(g) When some moles of NH_4I(s) are added to the equilibrium system at constant temperature: the value K_c increases. decreases. remains the same. the value of Q_c is greater than K_c. is equal to K_c. is less than K_c. the reaction must: run in the forward direction to restablish equilibrium. run in the reverse direction to restablish equilibrium. remain the same. It is already at equilibrium. the concentration of NH_3 will: increase. decrease. remain the same.Explanation / Answer
According to the Le-Charterlier's principle,
(1) If the temperature is raised, reaction will proceed in the direction in which some heat can destroy (absorbed) so that temperature of the system remains constant.
Thus increase in temperature shifts the equilibrium in the forward direction of those reactions which proceed with absorption of heat (endothermic reactions), and in the back ward direction of those reactions which proceed with the evolution of heat (exothermic reactions)
(2) If the pressure is increased, reaction will takes place in a direction which will bring about lowering f pressure. This implies that the equilibrium will shifts in the direction which produces the smaller no. of gas molecules.
(3) If the concentration of reactants is increased or product is removed , the reaction will take place in the forward direction. If the concentration of reactants decreases or increasing the concentration of products the reaction will take place in the backward direction.
(4) Catalyst speeds up both forward & backward reactions to the same extent but does not have any effect on Equilibrium point.
(5)---> When the no. of moles of reactants & products are same the addition of inert gas has no effect
----> for a reaction at constant pressure ,addition of an inert gas will shifts the equilibrium in the direction in
which there is increase in the no . of moles of the gases
NH4I(s) <----> NH3(g) + HI(g)
Kc = [products]/[reactants]
Upon addition of NH4I (ie) the concentration of reactant increases , forward reaction takes place there by the concentration of products increases.
So Kc remains the same
Since forward reaction takes place Kc > Qc
So Qc is less than Kc
The reaction must run in the forward direction to restablish equilibrium.
Since forward reaction takes place the concentration of products ie [NH3] will increases