Law of Conservation of Mass

Front

What is the Law of Conservation of Mass?

Back

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction. The total mass of reactants equals the total mass of products.

Front

What is a balanced chemical equation?

Back

A balanced chemical equation has the same number of each type of atom on both sides of the equation, ensuring that mass is conserved.

Front

Which of the following is a balanced equation? CH₄ + O₂ → CO₂ + 2H₂O, H₂ + O₂ → 2H₂O₄, 4Al + 3O₂ → 2Al₂O₃

Back

4Al + 3O₂ → 2Al₂O₃ is balanced.

Front

What does a subscript in a chemical formula indicate?

Back

A subscript indicates the number of atoms of the element in a molecule. For example, in H₂O, the '2' indicates there are two hydrogen atoms.

Front

What does a coefficient in a chemical equation represent?

Back

A coefficient indicates the number of molecules or moles of a substance involved in a reaction. For example, in 2H₂ + O₂ → 2H₂O, the '2' before H₂ and H₂O indicates two molecules.

Front

How do you balance the equation P₄ + O₂ → P₂O₃?

Back

The balanced equation is 1P₄ + 3O₂ → 2P₂O₃.

Front

If 24 g of magnesium reacts with 38 g of fluorine, what is the mass of magnesium fluoride produced?

Back

62 g of magnesium fluoride is produced.

Front

What is the difference between a subscript and a coefficient?

Back

A subscript indicates the number of atoms in a molecule, while a coefficient indicates the number of molecules in a reaction.

Front

What is the purpose of balancing chemical equations?

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Balancing chemical equations ensures that the Law of Conservation of Mass is upheld, meaning the same number of each type of atom is present before and after the reaction.

Front

What is an example of a chemical reaction that demonstrates the Law of Conservation of Mass?

Back

The reaction of hydrogen and oxygen to form water: 2H₂ + O₂ → 2H₂O shows that the total mass of reactants equals the total mass of products.