Understanding reactants and products is important when learning about chemical reactions. It also helps us grasp the idea of conservation of mass.

Definitions:

• Reactants: These are the starting materials that change during a chemical reaction.

• Products: These are the new materials created by the chemical reaction.

Conservation of Mass:

The law of conservation of mass says that in a closed system, mass can’t be made or vanished during a chemical reaction. This means the total weight of the reactants must equal the total weight of the products.

Total Mass of Reactants = Total Mass of Products

Example of a Chemical Reaction:

Let’s look at how hydrogen gas and oxygen gas combine to make water:

2H₂ + O₂ → 2H₂O

Breaking it Down:

• Reactants:

  • 2 molecules of hydrogen (H₂) weigh about 2 g each, giving us a total of 4 g (2 g × 2 = 4 g).
  • 1 molecule of oxygen (O₂) weighs about 32 g.

• Total mass of reactants: 4 g + 32 g = 36 g

• Products:

  • 2 molecules of water (H₂O) weigh about 18 g each, giving a total of 36 g (18 g × 2 = 36 g).

• Total mass of products: 36 g

Conclusion:

In this example, the mass is conserved. The total mass of the reactants (36 g) is the same as the total mass of the products (36 g). This shows how reactants and products demonstrate the conservation of mass in chemical reactions. It’s important to understand that matter is not created or destroyed during a reaction; this is a key idea in chemistry.