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Skills Page

Balancing Equations
Student Page, Class of 2000
 

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All chemical formulas should be represented in a balanced form, meaning that the number of atoms of each element are the same on both sides of the equation. In order to do this, the coefficients must be so, so that the number of atoms of each element is the same on both sides of the equation. The number of atoms of each element can be determined by multiplying the coefficient of the element by the subscript next to it. For example: 2Pb3O2 in this equation, there are 6 atoms of Pb (lead) and 4 atoms of O (oxygen).

 

Balancing equations: Br3 + O2 à BrO

In this equation we have on the left side (aka the reactant side), 3Br, 2O

On the right side (a.k.a the product side) we have

1Br, 1O

 

In order to balance this equation, we will adjust the coefficients (using trial and error) to achieve a balanced form which is:

2Br3 + 3O2 à 6BrO

Here, the same number of atoms of Bromine are on the left side as they are on the right side, and the same number of atoms of Oxygen are on the left side as they are on the right side.

Also, sometimes parenthesis are used: (SO4)3

In this example, the subscript 3 applies to both of the elements inside the parenthesis, so there are 3 atoms of Sulfur (S) and 12 atoms of Oxygen (O). The number outside the parenthesis is multiplied by the number of atoms that the element contains inside the parenthesis.

 

Other Examples

(see link at bottom of page for answers)

 

1. Cu +H2O à CuO + H2

2. Al(NO3)3 + NaOH à Al(OH)3 + NaNO3

3. KNO3 à KNO2 +O2

4. Fe + H2SO4 à Fe2(SO4)3 +H2

5. O2 + CS2 à CO2 + SO2

6. Cu + Cl2 à CuCl2

7. Mg + N2 à Mg3N2

8. C + O2 àCO2

9. CO + O2 àCO2

10. K + H2O àKOH + H2

11. NaOH + H2SO4 àNaSO4 + H2O

12. Al + H2SO4 àAl2(SO4)3 + H2

13. NH4NO2 àN2 + H2O

14. NH3 + CuO àCu + N2 + H2O

15. C2H6 + O2 àH2O + CO2

16. P4O10 + H2O àH3PO4

Mr. Curran's Lesson on Balancing Equations

Check your answers here

Practice Balancing More Equations

Back to Mr. Curran's Chemistry Page    

Please forward all questions, comments and criticisms to Gregory L. Curran.
© Copyright 2004 Fordham Preparatory School, All Rights Reserved.
Last Modified February 07, 2008