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 the reactants equals the total mass of the products.

Front

What are subscripts in a chemical formula?

Back

Subscripts are the small numbers written to the lower right of an element symbol in a chemical formula, indicating the number of atoms of that element in a molecule.

Front

In the chemical formula 3Fe₂O₄, what do the subscripts 2 and 4 represent?

Back

The subscript 2 indicates there are 2 iron (Fe) atoms, and the subscript 4 indicates there are 4 oxygen (O) atoms in one molecule of Fe₂O₄.

Front

What is a coefficient in a chemical equation?

Back

A coefficient is a number placed in front of a chemical formula in a reaction to indicate how many molecules or moles of that substance are involved.

Front

What is the coefficient in the equation 3H₂O?

Back

The coefficient is 3, indicating there are 3 molecules of water (H₂O).

Front

How do you determine if a chemical equation is balanced?

Back

A chemical equation is balanced when the number of atoms of each element is the same on both sides of the equation.

Front

What is the balanced equation for the reaction of hydrogen and oxygen to form water?

Back

2H₂ + O₂ → 2H₂O.

Front

If Bob puts 200 grams of ice into 900 grams of water, what is the total mass of the water after the ice melts?

Back

The total mass is 1,100 grams (200 g of ice + 900 g of water).

Front

What is the difference between a subscript and a coefficient?

Back

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

Front

What does a balanced chemical equation represent?

Back

A balanced chemical equation represents the conservation of mass, showing that the total mass of reactants equals the total mass of products.