For a reaction that is exothermic in the forward direction, a decrease in temperature will...?

[匿名]

2016-06-12 2:13 pm

1. For a reaction that is exothermic in the forward direction, a decrease in temperature will:
a) shift the position of equilibrium to the left
b) not shift the position of equilibrium
c) favor the formation of reactants
d) favor the formation of products

2. A positive ΔH and positive ΔS:
a) will never produce a spontaneous reaction
b) will always produce a spontaneous reaction
c) will only produce a spontaneous reaction if the increase in entropy times temperature is greater than the increase in enthalpy
d) will only produce a spontaneous reaction if the increase in enthalpy is greater than - T times the increase in entropy

回答 (1)

fooks

2016-06-12 2:26 pm

1.
According to Le Chatier's principle, decrease in temperature favors the exothermic reaction, i.e. the forward reaction.
Therefore, the equilibrium shifts to the right, and favors the formation of products.

..... The answer is : d) favor the formation of products.

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2.
ΔG = ΔH - TΔS

The reaction is spontaneous when ΔG < 0, i.e. ΔH - TΔS < 0
and thus TΔS > ΔH

...... The answer is : c) will only produce a spontaneous reaction if the increase in entropy times temperature is greater than the increase in enthalpy

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