Balancing Chemical Equations Using Oxidation Numbers

The unbalanced equation for the reaction of sulphur dioxide with bromine is as shown below:

${\mathrm{SO}}_2+{\mathrm{Br}}_2+{\mathrm{H}}_2\mathrm{O}\stackrel{ }{\to }{{\mathrm{SO}}_4}^{2-}+{\mathrm{Br}}^{-}+{\mathrm{H}}^{+}$

Construct a balanced equation for this reaction.

Write a balanced equation for the reaction of calcium with water.

Use the oxidation number method to balance the equation, ${\mathrm{V}}^{3+}+{\mathrm{I}}_2+{\mathrm{H}}_2\mathrm{O}\stackrel{ }{\to }{\mathrm{VO}}^{2+}+{\mathrm{I}}^{-}+{\mathrm{H}}^{+}$.

Use the oxidation number method to balance the equation, $\mathrm{HBr}+{\mathrm{H}}_2{\mathrm{SO}}_4\stackrel{ }{\to }{\mathrm{Br}}_2+{\mathrm{SO}}_2+{\mathrm{H}}_2\mathrm{O}$.

Use the oxidation number method to balance the equation, ${\mathrm{H}}_2{\mathrm{SO}}_4+\mathrm{HI}\stackrel{ }{\to }\mathrm{S}+{\mathrm{I}}_2+{\mathrm{H}}_2\mathrm{O}$.

Zinc metal reacts with ${{\mathrm{IO}}_3}^{-}$ ions in acidic solution. Construct a balanced ionic equation for this reaction, using the two half equations below:

$2{{\mathrm{IO}}_3}^{-}+12{\mathrm{H}}^{+}+10{\mathrm{e}}^{-}\stackrel{ }{\to }{\mathrm{I}}_2+6{\mathrm{H}}_2\mathrm{O}$

$\mathrm{Zn}\stackrel{ }{\to }{\mathrm{Zn}}^{2+}+2{\mathrm{e}}^{-}$

 Construct a balanced ionic equation for this reaction, using the two half equations below:

$2{{\mathrm{IO}}_3}^{-}+12{\mathrm{H}}^{+}+10{\mathrm{e}}^{-}\stackrel{ }{\to }{\mathrm{I}}_2+6{\mathrm{H}}_2\mathrm{O}$

$\mathrm{Zn}\stackrel{ }{\to }{\mathrm{Zn}}^{2+}+2{\mathrm{e}}^{-}$

Balance the given chemical equation by hit and trial method:

$\mathrm{Al}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\stackrel{ }{\to }{\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)$