Consider the reaction $$ \mathrm{P}_{4}(g) \longrightarrow 2 \mathrm{P}_{2}(g) $$ where \(K_{\mathrm{p}}=1.00 \times 10^{-1}\) at \(1325 \mathrm{~K}\). In an experiment where \(\mathrm{P}_{4}(g)\) is placed into a container at \(1325 \mathrm{~K}\), the equilibrium mixture of \(\mathrm{P}_{4}(\mathrm{~g})\) and \(\mathrm{P}_{2}(g)\) has a total pressure of \(1.00 \mathrm{~atm} .\) Calculate the equilibrium pressures of \(\mathrm{P}_{4}(g)\) and \(\mathrm{P}_{2}(g) .\) Calculate the fraction (by moles) of \(\mathrm{P}_{4}(g)\) that has dissociated to reach equilibrium.

Short Answer

Expert verified
The equilibrium pressures of P_4(g) and P_2(g) are approximately 0.8942 atm and 0.2116 atm, respectively, and the mole fraction of P_4(g) that has dissociated at equilibrium is 0.1058.

Step by step solution

01

Write the balanced chemical equation

The given balanced chemical equation for the reaction is: \[ \mathrm{P}_{4}(g) \longrightarrow 2 \mathrm{P}_{2}(g) \]
02

Set up the Equilibrium Constant expression

Since we have K_p given, we can write the equilibrium constant expression as: \[ K_p = \frac{(\mathrm{P}_{2})^2}{\mathrm{P}_{4}} \]
03

Set the initial condition for P_4(g) and dissociation

Let x be the moles of P_4(g) that dissociate to reach equilibrium. Then the initial pressures of P_4(g) and P_2(g) are: P_4 = P - x P_2 = 2x P_total is given as 1 atm.
04

Calculate the equilibrium pressures using K_p

Substitute the equilibrium pressures to the K_p expression: \[ 1.00 \times 10^{-1} = \frac{(2x)^2}{(1-x)} \] We can now solve for x: \[ 1.00 \times 10^{-1} = \frac{4x^2}{(1-x)} \] \[ 0.1 (1-x) = 4x^2 \]
05

Solve the equation for x

Rearrange and solve the quadratic equation for x: \[ 4x^2 + 0.1x - 0.1 = 0 \] Using the quadratic formula to solve for x, we get: \[ x = \frac{-0.1 \pm \sqrt{(-0.1)^2 - 4(4)(-0.1)}}{2(4)} \] Solving for the positive root (as x cannot be negative), we get: \[ x \approx 0.1058 \]
06

Calculate equilibrium pressures and mole fraction

Now, we can calculate equilibrium pressures using the values of x: P_4 = 1 - x = 1 - 0.1058 ≈ 0.8942 atm P_2 = 2x ≈ 0.2116 atm Finally, we can calculate the fraction (by moles) of P_4(g) that has dissociated to reach equilibrium: \[ \text{Mole fraction} = \frac{x}{1} = 0.1058 \] #Conclusion# The equilibrium pressures of P_4(g) and P_2(g) are approximately 0.8942 atm and 0.2116 atm, respectively, and the mole fraction of P_4(g) that has dissociated at equilibrium is 0.1058.

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