Question

sulfur dioxide and oxygen react to form sulfur trioxide, like this: 2so₂(g)+o₂(g)→2so₃(g) the reaction is exothermic. suppose a mixture of so₂, o₂ and so₃ has come to equilibrium in a closed reaction vessel. predict what change, if any, the perturbations in the table below will cause in the composition of the mixture in the vessel. also decide whether the equilibrium shifts to the right or left. perturbation change in composition shift in equilibrium the temperature is lowered. the pressure of so₂ will select to the right to the left (none) the temperature is raised. the pressure of so₃ will select to the right to the left (none)

Explanation:

Step - by - Step Format:

Step 1: Recall Le - Chatelier's principle for temperature change in exothermic reactions

For an exothermic reaction \(2SO_{2}(g)+O_{2}(g)
ightleftharpoons2SO_{3}(g)\), \(\Delta H<0\). When the temperature is lowered, according to Le - Chatelier's principle, the system will try to counteract the change. Since the forward reaction is exothermic (releases heat), lowering the temperature favors the forward reaction.
As the forward reaction is favored, more \(SO_{2}\) is consumed. So, the pressure of \(SO_{2}\) (which is proportional to its amount, \(P = n\frac{RT}{V}\), assuming \(V\) and \(T\) are related to the shift and \(R\) is constant) will decrease. And the equilibrium shifts to the right.

Step 2: Analyze the effect of raising the temperature

When the temperature is raised, the system will try to absorb the added heat. Since the reverse reaction is endothermic (\(\Delta H>0\) for the reverse reaction \(2SO_{3}(g)
ightleftharpoons2SO_{2}(g)+O_{2}(g)\)), raising the temperature favors the reverse reaction.
As the reverse reaction is favored, \(SO_{3}\) decomposes. So, the pressure of \(SO_{3}\) (using the ideal - gas law relationship \(P = n\frac{RT}{V}\)) will decrease. And the equilibrium shifts to the left.

Answer:

When the temperature is lowered:

• The pressure of \(SO_{2}\) will decrease.
• The equilibrium shifts to the right.

When the temperature is raised:

• The pressure of \(SO_{3}\) will decrease.
• The equilibrium shifts to the left.