A level Chemistry One marker HELP PLEASE URGENT

i have my mock tomoz and im ughhgh #

pls could someone help me with this q. i know the answer just no sure how they got to it

sulfur (IV) oxide reacts with water to for a solution containing ions. write an equation for this reaction. (1)
the answer is SO2 +H20 --> H+ + HSO3-

firstly i thought because there's a 4 next to the sulfur, the equation for sulfur oxide would be S2O4.
Secondly i don't understand why those are the ions it formed?

thank you

it should be SO2, however they put the (4) next to the sulfur cz sulfur(4) oxide and water react to form the sulfurous acid. and every acid has the H+ ion. so just minus 1 H from the sulfurous acid formula and you'll get the equation for the anion as well

no, I don't think you can just add a 4 because you would be creating atoms and that's not possible


and if I'm not mistaken when so2 reacts with water sulfurous acid is formed which has those respective ions ^^

ooh i see! thanks
but i dont get why the answer is SO2 and not S2O4? because by saying its sulfur (4) oxide its implying the sulfur has a 4+ charge right?

ooh i see! thanks
but i dont get why the answer is SO2 and not S2O4? because by saying its sulfur (4) oxide its implying the sulfur has a 4+ charge right?

yes. sulfur (IV) does have a 4+ charge. Its SO2 because oxygen always* has a 2- charge so you only need two oxygens to have an overall charge of 0 (4+ and two 2- charges)

*there are a few exceptions where the oxygen charge is not 2- (eg: H2O2 where oxygen has a 1- charge)

Sulphur (IV) oxide means that the oxidation state of sulphur is +4. O2 usually has an oxidation state of -4, so they balance out.

Think of the reaction between SO3 (sulphur (VI) oxide) and water:
SO3 + H2O => + H2SO4 <=> H+ + HSO4-
This gives you sulphuric acid.

Now do the same for SO2 (sulphur (IV) oxide) and water:
SO2 + H2O => H2SO3 <=> H+ + HSO3-

The equations are already balanced, so that makes it easier. Oxides of sulphur react with water to produce an acid. Since it asks for the equation in terms of ions, rather than write the acid (H2SO4, H2SO3) you can just write down the ions that it forms when the acid dissociates.