# Balancing Chemical Equations

A chemical equation describes in a formula the identities and quantities of substances involved in a chemical reaction. Rules for balancing :

• Balance the elements one at a time using coefficients.
• You cannot change the subscript numbers which would change the identity of the chemicals.
• The number of atoms of each element on the left of the yields arrow must equal the number of atoms of each element to the right.

## Word Problems

1. Sodium reacts with chlorine to form sodium chloride (NaCl)

2. Silver (Ag) and sulfur (S) combine to form silver sulfide (Ag2S)

3. Potassium chlorate (KClO3) decomposes into potassium chloride (KCl) and oxygen gas (O2)

4. Magnesium (Mg) and oxygen gas (O2) combine to form magnesium oxide (MgO)

5. Aluminum oxide (Al2O3) decomposes into aluminum and oxygen gas (O2)

6. Hydrogen gas (H2) reacts with nitrogen gas (N2) to form ammonia (NH3)

7. Hydrogen gas (H2) and oxygen gas (O2) combines to form water (H2O)

8. Phosphorus and oxygen gas (O2) combine to form phosphorus pentoxide (P2O5)

9. Carbon and iron oxide (Fe2O3) react to form iron and carbon monoxide (CO)

10. Potassium chloride (KCl) reacts with fluorine gas (F2) to form potassium fluoride (KF) and chlorine gas (Cl2)

11. Silver oxide (Ag2O) decomposes into silver and oxygen gas (O2)

12. Carbon dioxide (CO2) and water (H2O) react to form glucose (C6H12O6) and oxygen gas (O2)

## Balancing Chemical Equations Problems

1. ____ Na + ____ Cl   →   ____ NaCl

2. ____ Ag + ____ S   →   ____ Ag2S

3. ____ KClO3   →       ____ KCl + ____ O2

4. ____ Mg + ____ O2   →   ____ MgO

5. ____ Al2O3   →   ____ Al + ____ O2

6. ____ H2 + ____ N2   →   ____ NH3

7. ____ H2 + ____ O2   →   ____ H2O

8. ____ P + ____ O2   →   ____ P2O5

9. ____ C + ____ Fe2O3   →   ____ Fe + ____ CO

10. ____ KCl + ____ F2   →   ____ KF + ____ Cl2

11. ____ Ag2O   →   ____ Ag + ____ O2

12. ____ CO2 + ____ H2O   →   ____ C6H12O6 + ____ O2