Question

Tube worms that survive near geothermal vents of hydrogen sulfide rely on bacteria living inside them to obtain energy by the oxidation of H 2S to SO 4 2-. What is the overall change in the oxidation number of sulfur for this reaction?

Answer 1

Answer:

The overall change in the oxidation number of sulfur is 8.

Explanation:

Oxidation number is defined number assigned to an element in reaction which represent the loss or gain of electrons by an atom of an element in a compound.

In $H_2S$

let the oxidation number of S in hydrogen sulfide be x.

$(+1\times 2)+x=0$

x = -2

In $SO_4^{2-}$

let the oxidation number of S in sulfate ion be x.

$x+(-2\times 4)=-2$

x = -2 + 8 = +6

The overall change in the oxidation number of sulfur :

= [+6] - [-2] = 8

$S^{-2}\rightarrow S^{+6}+8e^-$