Q20.66 P - Chemistry: Molecular Nature Of Matter And Change

Question

The scenes and the graph relate to the reaction of  ${\mathbf{\text{X}}}_{\mathbf{\text{2}}}\mathbf{\text{(g)}}$ (black) with  ${\mathbf{\text{Y}}}_{\mathbf{\text{2}}}\mathbf{\text{(g)}}$ (orange) to form $\mathbf{\text{XY(g)}}$.

(a) If reactants and products are in their standard states, what quantity is represented on the graph by x?

(b) Which scene represents point 1? Explain. 

(c) Which scene represents point 2? Explain.

Step-by-Step Solution

Answer

1. X represents the standard free energy change of the reaction.
2. Scene A represents point 1.
3. Scene C represents point 2.

Step 1: Definition of Concept

Solubility: The maximum amount of solute that can be dissolved in the solvent at equilibrium is defined as solubility.

Constant of soluble product: For equilibrium between solids and their respective ions in a solution, the solubility product constant is defined. In general, the term "solubility product" refers to water-equilibrium insoluble or slightly soluble ionic substances.

Step 2:Find the quantity is represented on the graph by x

(a)

Consider the reaction given below,

 ${\text{X}}_{\text{2}}{\text{(g)+Y}}_{\text{2}}\text{(g)}\to \text{2XY(g)}$

Redraw the graph of the reaction as follows (Figure: 1),

Here, the free energy of the system is plotted against the extent of reaction,

The standard free energy equation is,

 ${\text{ΔG}}_{\text{rxn}}^{\text{°}}\text{=}\sum \text{m}{{\text{ΔG}}_{\text{f}}}^{\text{°}}\text{ (Products)- }\sum \text{n}{\text{ΔG}}_{\text{f}}^{\text{°}}\text{ (Reactants) }$

Since the gaseous are at a standard state, the value of X indicates the difference between the free energies of products and reactants. 

Thus, X represents the standard free energy change of the reaction.

Step 3: Explain which scene represents point 1

(b)

Consider the scene: A

Scene A corresponds to point 1 on the given graph. This point corresponds to the pure substance, it is not a mixture.

Step 4: Explain which scene represents point 2

(c)

Consider the Scene C:

In Scene C corresponds to point 2 on the graph. Point 2 represents equilibrium, for this reaction, products dominate at equilibrium. The graph shows the minimum in the curve is close to the X Y side.