How do I balance the equation for combustion of Si₂H₆?

How was this answer arrived at: 2 Si₂H₆ + 7 O₂ 4 SiO₂ + 6 H₂O

	Vocabulary
	balanced equation disilane stoichiometric coefficients

1. First, I'm going to try putting a 1 in front of the most complicated looking compound.

   1 Si₂H₆ +     O₂   SiO₂ +    H₂O

2. To balance the Si's, I must put a 2 in front of the SiO₂. That gives me 2 silicon atoms on each side.

   1 Si₂H₆ +     O₂ 2 SiO₂ +    H₂O

3. To balance the H's, I must put a 3 in front of the H₂O. That gives me 6 hydrogen atoms on each side.

   1 Si₂H₆ +     O₂ 2 SiO₂ + 3 H₂O

4. The right side has 7 oxygens. I'll write 7/2 in front of O₂ to give me 7 oxygens on the left side.

   1 Si₂H₆ + 7/2 O₂ 2 SiO₂ + 3 H₂O

5. I'll multiply everything through by 2 to get rid of the fraction. This isn't really necessary; the equation would be correctly balanced with fractional coefficients!

   2 Si₂H₆ + 7 O₂ 4 SiO₂ + 6 H₂O

For more about the individual steps I used, see 10 tips for balancing simple equations.

Author: Fred Senese senese@antoine.frostburg.edu

Copyright © 1997-2005 by Fred Senese
Comments & questions to fsenese@frostburg.edu
Last Revised 07/31/07.URL: http://antoine.frostburg.edu/chem/senese/101/reactions/faq/combustion-si2h6.shtml