How do I balance the equation for combustion of Si2H6?

How was this answer arrived at: 2 Si2H6 + 7 O2rightarrow 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 +     O2rightarrow   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 +     O2rightarrow 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 +     O2rightarrow 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 O2rightarrow 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 O2rightarrow 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



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