Question

In the discussion, write the equilibrium equations for the reactions studied in this lab (equations 3, 4, and 5). Determine whether the reaction is exothermic or endothermic and include heat (Q) as a product or reactant. Remember that there is only one equilibrium equation for a given system and the added reagents are not part of that equation. For each stress applied (reagent added, heat added or removed) identify the stress and explain the effect of the stress in detail, according to Le Chatelier's principle. Include which way the equilibrium shifted and why. Remember that the observations you made and recorded are not explanations; rather they are results needing to be explained.

Equation #3:

CoCl4^-2 (alcohol, blue) + 6H2O <--> Co⁺² 6H2O (aq, pink) + 4Cl^-

Equation #4

NH₄Cl (s) <--> NH₄⁺ (aq) + Cl^- (aq)

Equation #5

NaCl (s) <--> Na⁺ (aq) + Cl^- (aq)

Answer 1

According to Le - chatlier's principle,

1. Addition of reactants or removal of products shifts the equilibrium towards right side i.e products side.

2. Removal of reactants or addition of products shifts the equilibrium towards left side i.e reactants side.

3. Addition of heat favours endothermic reaction

4. Removal of heat favours exothermic reaction

5. Increase in pressure shifts the equilibrium towards less number of gaseous substances.

6. Decrease in pressure shifts the equilibrium towards more number of gaseous substances.

Equation3:

[CoCl₄]^2- (aq.) + 6 H₂O (l) <------------> [Co(H₂O)₆]²⁺ (aq.) + 4 Cl^- (aq.) ,       Q = -ve , exothermic

Equation4:

NH₄Cl (s) <-----------> NH₄⁺ (aq.) + Cl^- (aq.) , Q = + ve , endothermic

Equation5:

NaCl (s) < -------------> Na⁺ (aq.) + Cl^- (aq.) ,   Q = + ve , endothermic

Applying above rules we would be able to identify towards which the equilibrium position shifts.