Question

HBr + H2SO4 = SO2 + Br2 + H2O
Did S change oxidation number?

Answer 1

Yes

Step-by-step explanation:

The important rules for oxidation numbers are:

• The oxidation number of H in a compound is +1.
• The oxidation number of O in a compound is usually -2.
• The sum of the oxidation numbers in a compound is zero.

Thus, in your reaction, the oxidation numbers for S are:

`\rm HBr + H_(2)\stackrel{\hbox{+6}}{\hbox{S}}O_(4) \longrightarrow \, \stackrel{\hbox{+4}}{\hbox{S}}O_(2) +Br_(2) + H_(2)O\\\text{The oxidation number of S $\large \boxed{\textbf{changes from +6 to +4}}$}`