Synthesis is called a chemical reaction in which a compound is formed from elementary substances.
- The combustion of carbon is a synthesis reaction (the synthesis of carbon dioxide): $ C$ $ +$ $ O_2 $ $\longrightarrow $ $ CO_2$ - The synthesis of hydrogen chloride is: $H_2$ $ +$ $ Cl_2$ $\longrightarrow $ $ 2HCl$
Analysis is called a chemical reaction in which a compound is decomposed into elementary substances.
- The decomposition of water by electrolysis is an analysis reaction : $2H_2O$ $ \longrightarrow$ $ 2H_2$ $ +$ $ O_2$