Question

The following equilibrium reaction occurs in aqueous solutions when 0.1 M KSCN is mixed with 0.1 M Fe(NO₃)₃.

Fe(SCN)²⁺(aq) <----> Fe³⁺(aq) + SCN^-(aq)

Predict whether the following statements (in relation to the above equilibrium reaction in aqueous solution) are "True" or "False".

True False  Addition of 0.1 M KNO₃ causes the equilibrium to shift to the left (reactant side).
True False  Addition of 0.1 M Fe(NO₃)₃ does not affect the position of the equilibrium.
True False  Addition of 0.1 M CsSCN will have a similar effect on the position of the equilibrium as the addition of 0.1 M KSCN.
True False  In the addition of 0.1 M NaNO₃, NO₃^- reacts with Fe³⁺ to form Fe(NO₃)₃.
True False  Addition of 0.1 M KSCN causes the equilibrium to shift to the left (reactant side).
True False  Addition of 6 M NaOH causes the equilibrium to shift to the left because NaOH is a strong base and breaks the bonds in Fe(SCN)²⁺.
True False  Addition of 0.1 M NaNO₃ does not have as much influence on the position of the equilibrium.

Answer 1

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

Fe(SCN)2+(aq) <----> Fe3+(aq) + SCN-(aq)

Addition of 0.1 M KNO3 causes the equilibrium to shift to the left (reactant side). (TRUE)

In the addition of 0.1 M KNO3, NO3- reacts with Fe3+ to form Fe(NO3)3 so concentration of products increases so equilibrium shifts towards backward

Addition of 0.1 M Fe(NO3)3 does not affect the position of the equilibrium. (FALSE)

The addition increases the concentration of products so equilibrium shifts towards backward
Addition of 0.1 M CsSCN will have a similar effect on the position of the equilibrium as the addition of 0.1 M KSCN. (TRUE)

The addition increases the concentration of products so equilibrium shifts towards backward in both cases
In the addition of 0.1 M NaNO3, NO3- reacts with Fe3+ to form Fe(NO3)3. (TRUE)
Addition of 0.1 M KSCN causes the equilibrium to shift to the left (reactant side). (TRUE)
Addition of 6 M NaOH causes the equilibrium to shift to the left because NaOH is a strong base and breaks the bonds in Fe(SCN)2+. (FALSE)
Addition of 0.1 M NaNO3 does not have as much influence on the position of the equilibrium. (FALSE)