# Calculating Kc Equilibrium for PCl3 + Cl2 = PCL5 at 230°C

• kittymaniac84
In summary, to calculate Kc equilibrium for the reaction PCl3 + Cl2 = PCL5 at 230°C, you must first write out the balanced chemical equation and determine the initial concentrations of each reactant and product. Then, use the equilibrium constant expression and substitute in the equilibrium concentrations of each species to solve for Kc. Kc equilibrium is a measure of the extent of the reaction and can help predict the direction in which the reaction will proceed. Temperature affects Kc equilibrium, with higher temperatures causing an increase in Kc and a shift towards the products. The equilibrium constant can be calculated at any given temperature, but the value will change due to changes in concentrations. Pressure does not affect Kc, as it is only
kittymaniac84
The equilibrium constant Kc for the reaction, PCl3 (g) + Cl2 (g) = PCL5 (g),
equals 49 at 230°C. If 0.400 mol each of phosphorus trichloride and chlorine are
added to a 4.0 Liter reaction vessel, what is the equilibrium composition of the
mixture at 230°C?

Based on the given information, we can use the equilibrium constant (Kc) equation to calculate the equilibrium composition of the mixture at 230°C:

Kc = [PCL5]/[PCl3][Cl2] = 49

Since the initial amounts of PCl3 and Cl2 added to the reaction vessel are equal at 0.400 mol each, we can assume that at equilibrium, the amounts of both substances will decrease by the same amount (x) and the amount of PCL5 formed will be equal to the amount of PCl3 and Cl2 reacted. Therefore, the equilibrium concentrations can be represented as:

[PCl3] = 0.400 - x
[Cl2] = 0.400 - x
[PCL5] = x

Substituting these values into the Kc equation, we get:

49 = x/(0.400 - x)^2

Solving for x, we get x = 0.119 mol. This means that at equilibrium, 0.119 mol of PCL5 will be formed and the concentrations of PCl3 and Cl2 will be 0.281 mol each.

In summary, at 230°C, the equilibrium composition of the mixture will be 0.119 mol of PCL5, 0.281 mol of PCl3, and 0.281 mol of Cl2 in a 4.0 Liter reaction vessel. This calculation assumes that the reaction reaches equilibrium and no other factors, such as pressure or volume changes, affect the equilibrium composition.

## 1. How do you calculate Kc equilibrium for PCl3 + Cl2 = PCL5 at 230°C?

To calculate Kc equilibrium for this reaction, you need to first write out the balanced chemical equation and determine the initial concentrations of each reactant and product. Then, use the equilibrium constant expression, Kc = [PCL5]/([PCl3][Cl2]), and substitute in the equilibrium concentrations of each species. Finally, solve for Kc by plugging in the values and applying the necessary units.

## 2. What is the significance of Kc equilibrium in this reaction?

Kc equilibrium is a measure of the extent of a chemical reaction at a given temperature. It tells us the ratio of products to reactants at equilibrium and can help predict the direction in which the reaction will proceed.

## 3. How does the temperature affect Kc equilibrium for this reaction?

The equilibrium constant, Kc, is temperature-dependent. As the temperature increases, the value of Kc also increases. In this reaction, the equilibrium shifts towards the products at higher temperatures, meaning that more PCL5 is formed.

## 4. Can you calculate Kc equilibrium for this reaction at a different temperature?

Yes, the equilibrium constant, Kc, can be calculated at any given temperature. However, the concentrations of the reactants and products will change with temperature, so the value of Kc will also change.

## 5. How is the equilibrium constant affected when the pressure of the system is changed?

The equilibrium constant, Kc, is not affected by changes in pressure. This is because Kc is only dependent on the concentrations of the reactants and products, not the total pressure of the system.

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