A platinum catalyst is used in automobile catalytic converters to hasten the oxi

Question

A platinum catalyst is used in automobile catalytic converters to hasten the oxidation of carbon monoxide:
2CO(g)+O2(g)?Pt2CO2(g) ?H?=?566kJ
Suppose that you have a reaction vessel containing an equilibrium mixture of CO(g), O2(g), and CO2(g). Under the following conditions, will the amount of CO increase, decrease, or remain the same?

Part A

A platinum catalyst is added.

A platinum catalyst is added.

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Part B

The temperature is increased.

The temperature is increased.

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Part C

The pressure is increased by decreasing the volume.

The pressure is increased by decreasing the volume.

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Part D

The pressure is increased by adding argon gas.

The pressure is increased by adding argon gas.

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Part E

The pressure is increased by adding O2 gas.

The pressure is increased by adding gas.

Explanation / Answer

Part A: Remain the same

A catalyst speeds up both the forward and back reactions by exactly the same amount. Dynamic equilibrium is established when the rates of the forward and back reactions become equal. If a catalyst speeds up both reactions to the same extent, then they will remain equal without any need for a shift in position of equilibrium

Part B: Increase

The position of equilibrium also changes if you change the temperature. According to Le Chatelier's Principle, the position of equilibrium moves in such a way as to tend to undo the change that you have made.

If you increase the temperature, the position of equilibrium will move in such a way as to reduce the temperature again. It will do that by favouring the reaction which absorbs heat.

Since the reaction is exothermic, the equilibrium will shift towards left to absorb the heat.

Part C: Decrease

if we were to increase pressure by decreasing volume, the equilibrium shifts to the right, counteracting the pressure increase by shifting to the side with fewer moles of gas that exert less pressure

Part D: Decrease

When an inert gas is added to the system in equilibrium at constant pressure, then the total volume will increase. Hence, the number of moles per unit volume of various reactants and products will decrease. Hence, the equilibrium will shift towards the direction in which there is increase in number of moles of gases.

The equilibrium concentrations of the products and reactants do not directly depend on the pressure subjected to the system.

Part E: Decrease

If we are to add a species to the overall reaction, the reaction will favor the side opposing the addition of the species.

The equilibrium concentrations of the products and reactants do not directly depend on the pressure subjected to the system. However, a change in pressure due to a change in volume of the system will shift the equilibrium.

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