Balancing Chemical Equations

Front

What is a balanced chemical equation?

Back

A balanced chemical equation has equal numbers of each type of atom on both sides of the equation, following the law of conservation of mass.

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.

Front

How do you determine the number of atoms in a molecule?

Back

Count the subscripts in the chemical formula; if there is no subscript, it is assumed to be 1.

Front

What is the law of conservation of mass?

Back

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

Front

How do you balance a chemical equation?

Back

Adjust the coefficients of the reactants and products to ensure the same number of each type of atom on both sides.

Front

What is the balanced equation for the reaction of PCl5 with H2O?

Back

PCl5 + 4 H2O → 5 HCl + H3PO4.

Front

What is the balanced equation for the reaction of Mg with HCl?

Back

Mg + 2 HCl → MgCl2 + H2.

Front

What are the coefficients used to balance the equation: 2Ag2O → ? Ag + ? O2?

Back

2, 4, 1.

Front

How many hydrogen atoms are in H2O?

Back

There are 2 hydrogen atoms in one molecule of water (H2O).

Front

What is the balanced equation for Al + HCl → H2 + AlCl3?

Back

2 Al + 6 HCl → 3 H2 + 2 AlCl3.