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# Can a reaction be spontaneous if the entropy is negative?

## Can a reaction be spontaneous if the entropy is negative?

When the reaction is exothermic (negative ΔH) but undergoes a decrease in entropy (negative ΔS), it is the enthalpy term which favors the reaction. In this case, a spontaneous reaction is dependent upon the TΔS term being small relative to the ΔH term, so that ΔG is negative.

## Is a decrease in entropy spontaneous?

If a reaction is exothermic ( H is negative) and the entropy S is positive (more disorder), the free energy change is always negative and the reaction is always spontaneous….

Enthalpy Entropy Free energy
endothermic, H > 0 decreased disorder, S < 0 reaction is never spontaneous, G > 0

## What will be the sign of entropy for a spontaneous reaction?

A spontaneous reaction is one that releases free energy, and so the sign of ΔG must be negative. Consider first an endothermic reaction (positive ΔH) that also displays an increase in entropy (positive ΔS). It is the entropy term that favors the reaction.

## Which of the following is always true for a spontaneous reaction?

ΔG<0 is always true for spontaneous process.

## Is a reaction spontaneous at equilibrium?

A spontaneous reaction is a reaction that will proceed without any outside energy or driving force. A spontaneous reaction has an equilibrium constant greater than 1. A reaction will be nonspontaneous if the equilibrium constant is less than 1.

## When a system is at equilibrium the process is not spontaneous?

If a system is at equilibrium, ΔG = 0. If the process is spontaneous, ΔG < 0. If the process is not spontaneous as written but is spontaneous in the reverse direction, ΔG > 0.

## Which is always positive when a spontaneous process occurs?

The second law of thermodynamics states that for any spontaneous process, the overall ΔS must be greater than or equal to zero; yet, spontaneous chemical reactions can result in a negative change in entropy. Since the overall ΔS = ΔSsurroundings + ΔSsystem, the overall change in entropy is still positive.