half equations help!

I've just started chemistry and so I am not too sure how to do these following half equations:

SO4²- = SO2

SO4²- = S

SO4²- = H2S

= = ARROW

any help is greatly appreciated!
fanx :smile:

Reply 1

chrisl

(i) SO4(2-) + 2e- + 4H+ = SO2 + 2H20

First work out the oxidation numbers of the sulphur in the 2 species. Then balance these out using e-'s. Then balance overall change of the equation using H+ (or OH-0. And finally balance the number of H+'s in the equation using water. I think that's it! Not to good at them myself so was practicing by answering this qu. Try it on the other one.

Soz if its wrong

Reply 2

Revenged

cat123

I've just started chemistry and so I am not too sure how to do these following half equations:

SO4²- = SO2

SO4²- = S

SO4²- = H2S

= = ARROW

any help is greatly appreciated!
fanx :smile:

ok...

balance the equation with oxygen by adding water

SO₄ ²- = SO₂ + 2H₂ 0

then add the hydrogen ions to the left side of the equation

4H⁺ + SO₄ ²- + 2e^- = SO₂ + 2H₂ 0

you can check it is right by seeing if the equation is balanced in both atoms and adding electrons to balance the charge, which it does...

repeat that step process for the others and you should get...

SO₄ ²- + 8H⁺ + 6e^- = S + 4H₂0

SO₄ ²- + 10H⁺ + 8e^- = H₂ S + 4H₂ 0

Reply 3

chrisl

yey! i did get it right.