Product
In chemistry, a product is a new substance formed by a chemical reaction; products are written on the right side of a chemical equation.
Definition
Products are the new substances formed by a chemical reaction, written on the right side of the equation, and they have different properties from the reactants because the same atoms are rearranged into new bonds. The total mass of the products always equals the total mass of the reactants, since atoms are neither created nor destroyed. The actual amount of a product isolated in an experiment is compared with the theoretical yield calculated from the limiting reactant to give a percent yield, which side reactions, incomplete conversion, and losses during isolation all reduce. Under kinetic control the fastest-forming product dominates, while under thermodynamic control the most stable product dominates, and these two outcomes can differ for the same starting materials. At equilibrium, products are continually converting back into reactants at the same rate reactants form products.
Example
When baking soda meets vinegar, the fizzing bubbles are carbon dioxide gas, one of the products, along with water and a salt. Burning $16\text{ g}$ of methane with $64\text{ g}$ of oxygen in $CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$ produces $44\text{ g}$ of carbon dioxide and $36\text{ g}$ of water, $80\text{ g}$ of reactants in and $80\text{ g}$ of products out. Reacting $0.500\text{ mol}$ of benzene with excess nitric acid should in theory give $0.500\text{ mol}$ ($61.6\text{ g}$) of nitrobenzene; isolating $52.4\text{ g}$ in the lab gives a percent yield of $52.4/61.6 \times 100 = 85.1\%$.
Key Insight
Products of burning seem to vanish because many of them are invisible gases, which is why a burning log "disappears" into a small pile of ash even though weighing the smoke and gases shows the mass was never lost. Le Chatelier's principle explains why removing a product as it forms, such as by distilling it off, can drive a stubborn equilibrium reaction to completion, since the reverse reaction has less product available to work with.