A positive cell potential means that the reaction is spontaneous, and is true of all galvanic cells. This is seen in the equation , where "" is the number of electrons in moles that are transferred in the balanced equation, "" is Faraday's constant, and "" is the cell potential. A positive cell potential results in a negative  meaning the reaction is spontaneous.

A negative  value means that the equilibrium constant for the reaction is greater than 1, while a positive value mean the equilibrium constant is less than 1.

 for this reaction is negative, because the reactants have nineteen moles of gas while the products have only twelve. Entropy will always decrease in the system if there is a decrease in the number of moles of gas; we know that entropy must be negative for this reaction.

To determine the  at low temperature, use the following formula for Gibbs free energy.

The reaction is exothermic because we are giver that the enthalpy is negative.

The entropy, , is also negative, as discussed above.

This makes our equation .

Remember that temperature is given in Kelvin, and will never be negative. At very low temperatures, the  term will be dominant, and will be less than zero, making negative. A negative value for indicates that the reaction will be spontaneous.

A reaction is spontaneous if the change of Gibbs free energy  is less than zero.

The total reaction is the change .

For this question, the change of enthalpy  is negative, since D is lower in energy than A. There is a net release of energy, making the reaction exothermic. The question states that the change of entropy  is positive, and temperature is always positive when measured in Kelvin. We can return to the Gibbs free energy equation to see the result of these characteristics.

Both terms on the right side are always negative, and  would always be negative. The reaction would be spontaneous at any temperature.

A chemical reaction will be spontaneous when its change in Gibbs free energy, or , is negative. This value can be represented numerically by the equation:

First, let's look at the value for . The equation is more likely to yield a negative  value if this variable is below zero, so we want a negative value for . , however, is being subtracted, so a positive  value will give us a more negative . In combination, these conditions give us a negative value minus a positive one, which will always yield a negative answer.

If a reaction with a negative and a positive is always spontaneous, we can reason that a reaction with a positive and negative can never be spontaneous. This combination will yield a positive value minus a negative value, always resulting in a positive solution.

The first law of thermodynamics is the conservation of energy law. A cell that produces energy indefinitely is functionally a perpetual motion machine, and is prohibited by the first law.

The first law of thermodynamics states that the energy of the universe is constant because energy cannot be created or destroyed; however, it is possible for energy to be converted from one form to another. In this question the chair has kinetic energy in the beginning, but it loses all of this energy once it stops. This doesn’t mean that the kinetic energy is destroyed; it means that the kinetic energy is converted to another form of energy. Since it is sliding on a floor with a lot of friction (rough floor), the chair converts the kinetic energy to heat.

The second law of thermodynamics states that the entropy of the universe is always increasing. This law is irrelevant to the question.

In thermodynamics, no heat is exchanged in an adiabatic process, so heat is neither gained, nor lost. In an adiabatic compression temperature increases, but in an expansion temperature decreases.

A reaction with a zero free energy change is at equilibrium. At standard conditions, not at equilibrium, this reaction would have a Gibbs free energy change of –43 kJ/mol, would be spontaneous, and would be able to produce 43 kJ of useful work for every mole that reacts.

The first law of thermodynamics, conservation of energy, is not violated since the refrigerator is merely transforming electrical energy into work.

The second law of thermodynamics, increase of entropy, is violated since the entropy of a cooled house is lower, but there is no corresponding increase in entropy elsewhere. In order to cool an object in the system, and object in the surroundings must be heated.

The third law of thermodynamics deals with absolute zero and is not relevant.

The question states that the change in Gibbs free energy, , is negative. This means that the reaction is spontaneous. Second law of thermodynamics states that a spontaneous process always increases the entropy of the universe. Note that the second law only addresses the entropy of the universe; the change in entropy of a reaction could be either positive or negative. 

This reaction is exergonic (spontaneous) because the change in Gibbs free energy () is negative. It is also endothermic because the change in enthalpy () is positive.