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A certain reaction has negative values for both ? H and ? S . Therefore, the rea

ID: 841173 • Letter: A

Question

A certain reaction has negative values for both ?H and ?S. Therefore, the reaction

must be spontaneous at all temperatures.

cannot be spontaneous at any temperature.

can be spontaneous if the temperature is high enough.

can be spontaneous if the temperature is low enough.

has a positive free energy at any temperature.

must be spontaneous at all temperatures.

cannot be spontaneous at any temperature.

can be spontaneous if the temperature is high enough.

can be spontaneous if the temperature is low enough.

has a positive free energy at any temperature.

Explanation / Answer

can be spontaneous if the temperature is low enough.


When ?S is positive and ?H is negative, a process is always spontaneous

When ?S is positive and ?H is positive, a process is spontaneous at high temperatures, where exothermicity plays a small role in the balance.

When ?S is negative and ?H is negative, a process is spontaneous at low temperatures, where exothermicity is important.

When ?S is negative and ?H is positive, a process is not spontaneous at any temperature, but the reverse process is spontaneous.