# What is an example of a non-spontaneous process practice problem?

May 25, 2015

A spontaneous process is when a reaction takes place naturally without the help of a catalyst. Similarly, a non-spontaneous reaction takes place with the help of a catalyst.

An example of a spontaneous reaction is a paper turning yellow overtime while a non-spontaneous reaction might be setting a piece of wood on fire.

Spontaneity can be calculated through

\Delta G^\circ=\Delta H^\circ - T\Delta S^\circ

Delta H stands for change in enthalpy and T delta S is change is entropy.

Delta G < 0 = Spontaneous reaction
Delta G > 0 = Non-Spontaneous
Delta G = 0 = At equilibrium.

Try out this problem using the formula above.

Methane gas reacts with water vapor to produce a mixture of carbon monoxide and hydrogen according to the balanced equation below.

\text{CH}_4(g)+\text{H}_2\text{O}(g) \rightarrow \text{CO}(g)+3\text{H}_2(g)

The \Delta H^\circ for the reaction is +206.1 kJ/mol, while the \Delta S^\circ is +215 J/K • mol . Calculate the \Delta G^\circ at 25°C and determine if the reaction is spontaneous at that temperature.

I will comment the answer once you solve it!