In chemistry, a product is a chemical species resulting from a chemical reation transform into products after entering a high energy transition state. The number and type of atoms in the products of a chemical reaction are the same as the number and type of atoms in the reactants. However, the atoms form different chemical bonds with one another, so products have a different chemical identity from reactants and may be a different state of matter.

Identifying Products in Chemical Equations

By convention, products are on the righthand side of a chemical equation. The reaction arrow points toward products.

A + B → C + D

A and B are reactants and C and D are products.

In reversible reactions, arrows point both directions. This means the species on either side of the arrow act as both reactants and products.

A + B ⇌  C + D

Examples of Products in Chemistry

Here are some examples of products in chemistry, their reactants, and their balanced chemical equations:

• Water, H2O, is the product of the reaction between hydrogen and oxygen:
  2 H2+ O2 → 2 H2O
• Silver chloride, AgCl (s), is the product of the reaction between the silver cation and chloride anion in aqueous solution:
  Ag+(aq) + Cl– (aq) → AgCl (s)
• Nitrogen gas and hydrogen gas are the reactants forming ammonia as a product:
  N2+ 3 H2 → 2 NH3
• The oxidation of propane yields the products carbon dioxide and water:
  C3H8+ 5 O2 → 3 CO2 + 4 H2O

Products in Chemical and Physical Changes

The key difference between a chemical change is that the reactants differ from the products in a chemical change, but are the same in a physical change. In other words, no chemical reaction occurs in a physical change, although the reactant may change its state of matter.

For example, melting ice into water is an example of a physical change. The following equation represents the process:

H2O(s) → H2O(l)

The chemical formulas of the reactants and products are the same.

How to Predict Products of a Reaction

Predicting the products of a chemical reaction is mostly a matter of recognizing the  possible between two reactants. For example, if the reactants are a hydrocarbon and oxygen, it’s a safe bet the products are carbon dioxide and water. A single reactant breaks into multiple products via a decomposition reaction. Two elements combine to form a compound in a ratio that fills their valence electron shells.