Question

Match the action to the effect on the equilibrium position for the reaction N2(g) + 3H2(g) ⇌ 2NH3(g). Match Term Definition Increasing the pressure A) No effect Removing hydrogen gas B) Shift to the right Adding a catalyst C) Shift to the left

Answer 1

Answer:

1) Increasing the pressure          C) Shift to the right

2) Removing hydrogen gas        A) Shift to the left  

3) Adding a catalyst                     B) No effect

Explanation:

• Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.

1) Increasing the pressure:

• When there is an increase in pressure, the equilibrium will shift towards the side with fewer moles of gas of the reaction. And when there is a decrease in pressure, the equilibrium will shift towards the side with more moles of gas of the reaction.

• The reactants side (left) has 4.0 moles of gases and the products side (right) has 2.0 moles of gases.

• So, increasing the pressure will shift the reaction to the side with lower moles of gas (right side).

• so, the right match is: C) Shift to the right.

2) Removing hydrogen gas:

• Removing hydrogen gas will decrease the concentration of the products side, so the reaction will be shifted to the lift side to suppress the decrease in the concentration of hydrogen gas by removing.

• so, the right match is: A) Shift to the left.

3) Adding a catalyst:

• Catalyst increases the rate of the reaction without affecting the equilibrium position.

• Catalyst increases the rate via lowering the activation energy of the reaction.

• This can occur via passing the reaction in alternative pathway (changing the mechanism).

• The activation energy is the difference in potential energies between the reactants and transition state (for the forward reaction) and it is the difference in potential energies between the products and transition state (for the reverse reaction).

• in the presence of a catalyst, the activation energy is lowered by lowering the energy of the transition state, which is the rate-determining step, catalysts reduce the required energy of activation to allow a reaction to proceed and, in the case of a reversible reaction, reach equilibrium more rapidly.

• with adding a catalyst, both the forward and reverse reaction rates will speed up equally, which allowing the system to reach equilibrium faster.

• so, the right match is: B) No effect.