Thermodynamics and Thermochemistry
21.0 Coupled Reactions
21.0 Coupled Reactions
When $?G = –Ve$ the reaction is spontaneous and when $?G = +Ve$ the reaction is non-spontaneous. A non spontaneous reaction can also be made spontaneous in case it is carried simultaneously with another reaction which is spontaneous and has a very large negative free energy. Such reactions are said to be coupled reactions. e.g. Biosynthesis of sucrose from glucose and fructose has +ve value of $?G.$ It can be driven when coupled with hydrolyses at A.T.P.
$$Glu\cos e{\text{ }} + {\text{ }}Fructose{\text{ }} + {\text{ }}ATP \to Sucrose{\text{ }} + {\text{ }}ADP$$
$$\Delta G = - 8kJ\;mo{l^{ - 1}}$$
