Question

The reaction,
$C_2{H}_4\left(g\right)+H_2\left(g\right)\rightleftharpoons C_2{H}_6\left(g\right);\Delta H=-32.7kcal$ is carried out in a vessel. The equilibrium concentration of $C_2{H}_4$ can be increased by:

• A. Increasing the temperature
• B. Decreasing the pressure
• C. Removing some hydrogen
• D. All of the above

Answer 1

The correct option is D All of the above

The reaction,
$C_2{H}_4\left(g\right)+H_2\left(g\right)\rightleftharpoons C_2{H}_6\left(g\right);\Delta H=-32.7kcal$ is carried out in a vessel. The equilibrium concentration of $C_2{H}_4$ can be increased by increasing the temperature, decreasing the pressure and removing some hydrogen.
Negative value of enthalpy change indicates exothermic reaction. When temperature is increased, the equilibrium will shift towards reactants so that heat is absorbed during the reaction. This will nullify the effect of increase in temperature.
When pressure is decreased, the equilibrium will shift towards reactants ( which have more number of moles of gaseous species than products) so that pressure increases during the reaction. This will nullify the effect of decrease in pressure.
When one of the reactants (hydrogen) is removed, the equilibrium will shift to left so that more and more ethane is converted into ethene and hydrogen.
According to Le Chatelier's principle, when a system at equilibrium is disturbed, the position of the equilibrium shifts in a direction so that the effect of the change is nullified.