Question

The reaction of sulphur in alkaline medium is the below:
$S _{8( s )}+ a OH ^{-}_{( aq )} \rightarrow b S ^{2-}_{( aq )}+ c S _{2} O _{3}{ }^{2-}( aq )+ d H _{2} O _{(\ell)}$
The values of '$a$' is

Answer 1

for balancing in basic medium add equal number of $OH^\ominus$ that of $H^+$
$2S _{8}+12 H _{2} O +24 OH^\ominus \longrightarrow 8 S ^{2-}+4 S _{2} O _{8}^{2-} +24 H _{2} O$
$2 S _{8}+24 OH^\ominus \rightarrow 8 S ^{2-}+4 S _{2} O _{8}^{2-}+12 H _{2} O$
$S _{8}+12 OH^\ominus \rightarrow 4 S ^{2-}+2 S _{2} O _{8}^{2-}+6 H _{2} O$
$a =12$