Question

At 1000k the value of Kp is 20R for decomposition of PCl5 then find value of Kc?

Answer 1

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Answer 2

Answer:

The value of $K_{c}$ for decomposition of $PCl_{5}$ calculated is $0.02$.

Explanation:

Given data,

At $1000K$, the value of $K_{p}$ for decomposition of $PCl_{5}$= $20R$

The value of $K_{c}$ for decomposition of $PCl_{5}$ =?

Now, the decomposition of $PCl_{5}$ is shown below:

• $PCl_{5} (g) \rightarrow PCl_{3} (g)+ Cl_{2} (g)$

Here,

• $K_{p}$ is the equilibrium constant used when concentrations are expressed in atmospheric pressure.
• $K_{c}$ is the equilibrium constant used when concentrations are expressed in molarity.

The relationship between $K_{p}$ and $K_{c}$ is given below:

• $K_{p} = K_{c} (RT)^{\Delta n}$       -------equation (1)

Here,

• R = Gas constant
• T = Temperature
• Δn = The difference in the total number of moles of the gaseous products and the reactants.

As we can see from the above reaction:

• The number of moles of the gaseous products = $2$
• The number of moles of the gaseous reactants = $1$
• Δn = $2-1$ = $1$

After substituting the values of Δn, temperature and $K_{p}$ in equation (1), we get:

• $20R = K_{c} (R\times 1000)^{1}$
• $K_{c} = \frac{20}{1000}$
• $K_{c} = 0.02$

Hence, the value of $K_{c}$ for decomposition of $PCl_{5}$ = $0.02$.