#SPONTANEOUS PROCESSES FREE#

These are not a chemical reactions, because no new products are made.

With potassium chloride, the cooling is much more noticeable. When everyday table salt, sodium chloride, dissolves in water, the mixture cools slightly. When some salts dissolve in water, there is a cooling effect. Thionyl chloride is a well-known dehydrating reagent, but this reaction is not usually seen in classrooms because of its unfriendly reagents and products. The release of a large number of moles of gas in this reaction results in a large entropy gain that drives it forward. Since ΔG is negative, this endothermic reaction is spontaneous.Īdding thionyl chloride to cobalt(II) chloride hexahydrate results in an endothermic reaction.ĬoCl 2♶H 2O (s) + 6 SOCl 2 (l) → CoCl 2 (s) + 12 HCl (g) + 6 SO 2 (g) 058 - Spontaneous Processes In this video Paul Andersen discriminates between spontaneous (or thermodynamically favored) processes and those that are not spontaneous. NaHCO 3 (s) + HCl (aq) → NaCl (aq) + H 2O (l) + CO 2 (g) When solids become liquids or gases, the entropy (the number of ways the particles and energy in a system can be arranged) increases, hence endothermic reactions generally involve a change of state.Īt least one of the reactants will usually be solid, and at least one of the products will be a liquid or gas. Hence these reactions are spontaneous only if the entropy increase is sufficient to overpower the unfavorable enthalpy change.

#SPONTANEOUS PROCESSES FREE#

The chemicals involved lose free energy by heating up their surroundings.Įndothermic reactions are those with positive values of ΔH.įor these reactions, ΔG will be negative only if TΔS is bigger than ΔH. The overall situation is summed up in the Gibbs expression for reaction free energy:Įxothermic reactions have negative values of ΔH.

Hence reactions are spontaneous only when ΔG, the change in free energy, is negative. Spontaneous Reactions: The change in the Gibbs free energy in a spontaneous reaction is negative (G < 0). Nonspontaneous Reactions: Nonspontaneous reactions require an energy input to proceed. Chemical reactions can only proceed spontaneously if the total free energy of the products is less than the reactants. Spontaneous Reactions: Spontaneous reactions do not require energy input to proceed under a set of conditions.

Spontaneous processes