C (s) + 2 H2 (g) = CH4 (g)
A reaction is when two or more pure substances combine with each other to form another identity of pure substances. In general from, it is written as:
A + B → C + D
The substances A and B are the reactants, while the substances C and D are the products. Therefore, in a reaction, the products are found at the end or right side of the reaction.
