Defining a Reactant
A reactant is a substance that is present at the start of a chemical reaction and is consumed during the reaction to form new substances. Reactants are the initial ingredients that undergo a chemical change.
Section 2: Reactants vs. Products
In a chemical equation, reactants are always written on the left side of the arrow (→), while the new substances formed, called products, are written on the right. The arrow indicates the direction of the reaction, showing the transformation of reactants into products.
Section 3: A Practical Example
A classic example is the reaction that forms water from hydrogen and oxygen. The chemical equation is 2H₂ + O₂ → 2H₂O. In this case, hydrogen gas (H₂) and oxygen gas (O₂) are the reactants, and water (H₂O) is the product.
Section 4: Why Are Reactants Important?
Understanding reactants is fundamental to chemistry because they determine what products can be formed and how much can be produced. The properties and quantities of reactants dictate the outcome and efficiency of any chemical reaction, from baking a cake to industrial manufacturing.