Equilibrium

[Temperature101]

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If the following reaction is carried out in a closed steel reaction vessel, what will be observed for the pressure of the system if the temperature is doubled?

A(g) + B(g) <--------------> C(g) + D(g) + E(g) delta H = -112 kJ/mole

A. The pressure will remain the same.
B. The pressure will increase by less than 100%.
C. The pressure will exactly double
D. The pressure will increase by more than 100%.


I know A and C are out...Why it's B instead of D?

 

[MedPR]

I think this is more a question of real/ideal gas than it is an equilibrium question.

Real gases have volume, so the pressure will increase a little less than you would expect.

 

[Temperature101]

I think this is more a question of real/ideal gas than it is an equilibrium question.

Real gases have volume, so the pressure will increase a little less than you would expect.

You are right but it's in the equilibrium chapter of BR gen chem.

 

[PlumbLine]

I would answer B. I don't know for certain if my logic is sound, but this is my reasoning: If you consider the ideal gas law, doubling the temperature would double the pressure. However this reaction is exothermic and is in equilibrium, so adding heat will push the reaction toward the reactants (which are fewer in moles), which lowers the pressure. Therefore you can't double the pressure by doubling the temperature.

 

[Dasypus]

I would answer B. I don't know for certain if my logic is sound, but this is my reasoning: If you consider the ideal gas law, doubling the temperature would double the pressure. However this reaction is exothermic and is in equilibrium, so adding heat will push the reaction toward the reactants (which are fewer in moles), which lowers the pressure. Therefore you can't double the pressure by doubling the temperature.

This is totally right.

 

[silverlion]

Yeah! I was thinking along similar lines... I would have picked B.

 

[Temperature101]

I would answer B. I don't know for certain if my logic is sound, but this is my reasoning: If you consider the ideal gas law, doubling the temperature would double the pressure. However this reaction is exothermic and is in equilibrium, so adding heat will push the reaction toward the reactants (which are fewer in moles), which lowers the pressure. Therefore you can't double the pressure by doubling the temperature.

Thanks...Got it...TBR takes almost a whole page to explain it... These are the kind of questions I heard that MCAT throw at us. So if you dont pay attention to details, you are screwed.