Final answer:
The reactants in the given equation are water (H2O) and oxygen gas (O2), but the equation itself is not balanced. A correct and balanced reaction between hydrogen and oxygen would be 2H2 + O2 → 2H2O.
Step-by-step explanation:
The reactants in the chemical equation H2O + O2 → 3O + H2 are water (H2O) and oxygen gas (O2). Reactants are the starting substances in a chemical reaction that undergo a change to form new substances called products. However, it's important to note that the given chemical equation is not balanced and does not represent a typical reaction between hydrogen and oxygen. A more accurate representation of a reaction between hydrogen and oxygen would be 2H2 + O2 → 2H2O, where elemental hydrogen (H2) and elemental oxygen (O2) react to form water (H2O) as the product. This balanced equation adheres to the Law of Conservation of Mass, where the number of atoms of each element is the same on both sides of the equation.