Question

Consider the elementary gas-phase reversible reaction A 3C Pure A enters at a temperature of 400 K and a pressure of 10 atm. At this temperature, KC 0.25(mol/dm3)2. Calculate the equilibrium conversion for each of the following situations:

Answer 1

Answer:

• 39%

Explanation:

The equilibrium equation is:

          $A\rightleftharpoons 3C$

The initial concentration of A can be calculated from the ideal gas equation:

                 $pV=nRT\\\\n/v=p/(RT)\\\\C_A=\dfrac{10atm}{0.08206(atm-dm^3/K-mol)/times 400K}\\\\C_A=0.304mol/liter$

Determine the conversion of substance A to substance C using an ICE table and the Kc constant:

             A               ⇄          3C

I            0.304                        0

C             - x                          + 3x

E          0.304 - x                   3x

         $K_c=0.25=\dfrac{(3x)^3}{(0.304-x)}$

Solve for x:

You need to use a graphing calculator:

• 108x³ = 0.304 - x

• 108x³ + x - 0.304 = 0

• x ≈ 0.1195 mol/liter

Then:

           $C_A=0.304mol/liter-0.1195mol/liter=0.1845mol/liter\\\\C_C=3\times 0.304mol/liter=0.912mol/liter$

The equilbrium conversion is:

           $\% = [0.304mol/liter-0.1845mol/liter]/(0.304mol/liter)\times 100$

           $\% \approx 39\%$