Silicon is produced for the chemical and electronics industries by the following reactions. Give the balanced equation for each reaction. (Use the lowest possible coefficients. Use the pull-down boxes to specify states such as (aq) or (s). If a box is not needed, leave it blank.)
a. SiO2 (s) + C(s) + Si(s) + CO(g) SiO2(s) + C(s) Si(s) + CO(g)
b. Liquid silicon tetrachloride is reacted with very pure solid magnesium, producing solid silicon and solid magnesium chloride. + +
c. Na2 SiF6(s) + Na(s) + Si(s) + NaF(s) Na2SiF6(s) + Na(s) Si(s) + NaF(s)

Balancing a chemical equation means the same number of individual and overall atoms on the reactant side is equal to the same number of individual and overall atoms on the product side. This is based on the law of conservation of matter which states that matter can neither be created nor destroyed, hence the no atom must be unaccounted for on any side.

The balancing of these equations seem to test the knowledge of a particular trick in balancing of equation - which will be highlighted as the equation is balanced

(a) To balance

SiO₂(s) + C(s) ⇒ Si(s) + CO(g)

The balanced equation will be

SiO₂(s) + 2C(s) ⇒ Si(s) + 2CO(g)

NOTE: The best way to address equations like this to balance the uniatomic element last.

(b) SiCl₄(l) + Mg(s) ⇒ Si(s) + MgCl₂(s)

The balanced equation will be

SiCl₄(l) + 2Mg(s) ⇒ Si(s) + 2MgCl₂(s)

NOTE: As noted earlier, the uniatomic molecule should be balanced last

(c) To balance

Na₂SiF₆(s) + Na(s) ⇒ Si(s) + NaF(s)

The balanced equation will be

Na₂SiF₆(s) + 4Na(s) ⇒ Si(s) + 6NaF(s)

NOTE: As noted earlier, the uniatomic molecule should be balanced last

Please, always sum the number of individual and overall atoms on both sides when you are done answering questions like this just to be sure.