Question

PLEASE ANSWER THOROUGHLY AND BREAK DOWN EACH STEP. THANK YOU!!

Characteristics of Chemical Equilibrium

The purpose of this lab is to investigate how changing various factors affect an equilibrium system. This lab consists of four independent activities. Each activity changes a component (concentration, temperature, and pressure) in an equilibrium system. Students observe how the changes affect the equilibrium system and analyze the changes using Le Chatelier’s Principle.

Please explain your answers to the following questions using Le Chatelier’s Principle.

Activity A: Nature of Equilibrium

            HIn (aq)    ↔     H⁺(aq)     +      In^– (aq)        …… (A)

            Colorless                                    Pink

            H⁺(aq)       +     OH^-(aq) →     H₂O (l)

If HCl solution is added to the solution in equilibrium A, would the solution become more pink or less pink?

If NaOH solution is added to the solution, which direction would the equilibrium shift to? Would the color become more pink or less pink when NaOH solution is added to the equilibrium?

Activity B: Effect of Concentration

            Fe³⁺⁽aq)      +        SCN^-(aq)       ↔     FeSCN²⁺(aq) ………   (B)

            yellow                     colorless                 red

            Fe³⁺(aq)       +        H₂PO₄^-(aq)   →     FeH₂PO₄²⁺(aq)

            yellow                    colorless                 colorless

Which direction would the equilibrium shift to if Fe(NO₃)₃ solution is added to the equilibrium B?

Which direction would the equilibrium shift to if Na₃PO₄ is added to the equilibrium B?

Activity C: Effect of Temperature

1. Fe³⁺⁽aq)      +       SCN^-(aq)       ↔     FeSCN²⁺(aq)       is an exothermic reaction.

yellow                 colorless                     red

Would the color of the solution become more red or less red if the temperature is increased? What happens if the temperature is decreased?

2. Co(H₂O)₆²⁺ (aq)    +     4Cl^–(aq)    ↔     CoCl₄^2- (aq)     +    6H₂O (l)

pink                                                               blue

When the solution is heated to boiling, it turns from pink to blue.

Is this reaction endothermic or exothermic?

Bonus: if AgNO₃ is added to the above blue solution, would the solution change color back to pink? If HCl is then added to the solution, would the color change again?

Activity D: Effect of Pressure

2 CO₂(g)    +      H₂O(l)   ↔   CO₂ (aq)   +   H⁺(aq)     +   HCO₃^-(aq)

The reaction forms equilibrium in a large syringe with changeable volume.

Would the solution become more acidic or less acidic when the volume is increased? What happens if the volume is decreased?

Answer 1

A. On adding HCl to the reaction [H+] will increase, resulting in higher concetration of product. As per Le Chatelier's principle, the system wants to remain in equilibrium. However, due to increase in concentration of product reaction will move in backward direction and solution will become less pink.

On adding NaOH as reactant, the reaction will move in forward to maintain the equilibrium. Also, addition of NaOH will result in formation of water as product and solution will become less pink. Even though the reaction have moved in forward direction, [In-] have not changed since [HIn] have not been incresed. It is due to the addition of other reactant that the reaction is moving in forward direction, leading to formation of water which will dilute the peoduct.

B. Addition of Fe(NO3)3 increases the concentration of reactant i.e. Fe+3. Due to the increase in the reactant concentrtaion, equilibrium will shift in forward direction.

On adding Na3PO4, equilibrium shifts in forward direction as the reactant Fe+3 combines with it leading to the formation of (FeH2PO4)2- as product.

C. Exothermic reaction means heat is released. Thus,

A B + heat for an exothermic reaction

On increasing the temprature, reaction will move in backward direction to utilise the excess heat and solution will become less red.

If temperature is decreased, reaction will move in forward direction to release heat and solution wil become red.

On increasing the temperature, reactions moves in forward direction direction resulting in blue solution. This means the process is endothermic and when extra heat is provided, the equilibrium shifts in forward direction.