Consider the following system at equilibrium at 25^∘ C : PCl3(g)+Cl2(g) ⇌PCl5(g) ΔG^∘=-92.50

step 1 So given the reaction that we have, we have a delta G naught value, negative 92 .50 kilojoules.

Consider the following system at equilibrium at 25^∘ C :...

Consider the following system at equilibrium at $25^{\circ} \mathrm{C}$ : $$\mathrm{PCl}_{3}(g)+\mathrm{Cl}_{2}(g) \rightleftharpoons \mathrm{PCl}_{5}(g) \quad \Delta G^{\circ}=-92.50 \mathrm{~kJ}$$ What will happen to the ratio of partial pressure of $\mathrm{PCl}_{5}$ to partial pressure of $\mathrm{PCl}_{3}$ if the temperature is raised? Explain completely.

Consider the following system at equilibrium at $25^{\circ} \mathrm{C}$ :
$$\mathrm{PCl}_{3}(g)+\mathrm{Cl}_{2}(g) \rightleftharpoons \mathrm{PCl}_{5}(g) \quad \Delta G^{\circ}=-92.50 \mathrm{~kJ}$$
What will happen to the ratio of partial pressure of $\mathrm{PCl}_{5}$ to partial pressure of $\mathrm{PCl}_{3}$ if the temperature is raised? Explain completely.

Key Concepts

Chemical Equilibrium

Chemical equilibrium is a state in which the forward and reverse reactions occur at the same rate, so that the concentrations (or partial pressures for gases) of the reactants and products remain constant over time. In any reversible reaction, equilibrium is achieved when the reaction conditions allow for a balanced conversion between reactants and products, as described by the equilibrium constant expression.

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, such as temperature, pressure, or concentration, the system will adjust itself to counteract the imposed change and re-establish equilibrium. For exothermic reactions, increasing the temperature shifts the equilibrium toward the reactants to absorb the added heat.

Temperature Dependence of the Equilibrium Constant

The equilibrium constant (K) is temperature-dependent, and its value can change with temperature based on the enthalpy change of the reaction. For exothermic reactions, an increase in temperature generally leads to a decrease in K, which means that at the higher temperature the relative amount of product formed decreases compared to the reactants.

Gibbs Free Energy and the Equilibrium Constant

The relationship between Gibbs free energy and the equilibrium constant is given by the equation ?G° = -RT ln K, where ?G° is the standard Gibbs free energy change, R is the universal gas constant, and T is the temperature. This equation shows how changes in temperature can affect the equilibrium position by altering the value of K; for exothermic reactions with a negative ?G°, a temperature increase makes the natural logarithm term smaller, indicating a decrease in K.

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