Final answer:
Chemical reactions are classified based on how substances are transformed; synthesis combines substances, decomposition breaks them down, combustion involves oxygen, single replacement involves ions swapping places, and double replacement involves the exchange of cations between compounds.
Step-by-step explanation:
To classify chemical reactions, we can look at the patterns in which substances react and form products. A synthesis reaction involves elements or compounds combining to form a single new substance. Conversely, a decomposition reaction starts with a single compound that breaks down into two or more new substances. When oxygen is a reactant and combines with a compound to form oxides, this is known as a combustion reaction. If a reaction involves one ion replacing another in a compound, this is a single replacement reaction. Lastly, if a reaction has two compounds in the reactants and the cations switch partners, forming two new compounds, this is a double replacement reaction.
It's important to note that the number of products or reactants alone does not necessarily determine the type of reaction. Instead, the transformation of substances—how they are broken down or combined—dictates the reaction classification. Also, whether a reaction is considered a redox reaction depends on changes in oxidation numbers, which reflect the transfer of electrons between substances.