Question

Can a combination reaction be reversed? Justify your answer with an example.

Answer 1

1. Combination reaction:
2. A chemical reaction in which two or more simple substances are combined to form or single substance is called a combination reaction, which is generally a result of a spontaneous process.
3. Yes, a combination reaction can be reversed and that is called a decomposition reaction where a single substance is broken down into 2 or more simpler substances by the application of heat electricity, or light, this generally is a non-spontaneous process.

For example:

1. When Hydrogen and Oxygen combine water is produced. This is a highly exothermic process.

$\underset{(Hydrogengas)}{\underbrace{2H_2\left(g\right)}}+\underset{(Oxygengas)}{\underbrace{O_2\left(g\right)}}\to \underset{\left(Water\right)}{\underbrace{2H_{2}O\left(l\right)}}+Heat$

2. When the process of electrolysis is performed on the water then hydrogen and oxygen gas are obtained in the ratio of 2:1, which is the reverse of a combination reaction.

$\underset{\left(Water\right)}{\underbrace{2H_{2}O\left(l\right)}}\stackrel{Electricity}{\to }\underset{(Hydrogengas)}{\underbrace{2H_2\left(g\right)}}+\underset{(Oxygengas)}{\underbrace{O_2\left(g\right)}}$