[confusedstud]

When electron are transferred from one party to another then it is considered a redox reaction.

So when this reaction occurs H2+F2 2HF how can we say electron is transferred? Because aren't the electrons shared with each other?

Also, in Lewis acid-base reactions such as SO3+H2O H2SO4 electrons are transferred but they aren't redox (because the oxidation state remains the same).

What would be the explanation on why the first reaction is redox while the second is not in terms of electron transfer?

[aHerraez]

When discussing redox, we proceed by calculating the formal valence of each element and see if that changes in the reaction. Then, it is gaining or losing electrons.
In molecular hydrogen, since both atoms are equal their valence (or oxidation state) is zero.
So...  can you follow?

[confusedstud]

I think I kinda understand it more now. However, I was thinking of the reaction SO3+H2O H2SO4 I can't see how the electron pair gets transferred to the sulfur trioxide molecules. It seems more like the double bonds connecting the O to the S is broken and it takes the 4eO-H and the H gives 2 electrons to the other oxygen to me..

What prior knowledge do I need to understand this better? Because right now I've not learned about reaction mechanics and stuff like that I just got introduced to the Lewis acid base stuff on YouTube.

Thanks for the help

[Dan]

I think I kinda understand it more now. However, I was thinking of the reaction SO3+H2O H2SO4

Determine the oxidation numbers for each atom on each side of the arrow. Compare the results on each side. If there is a change, it is a redox reaction.

Example:

C + O₂ CO₂

C: 0 on the left; +4 on the right
O: 0 on the left; -2 on the right

Conclusion: This is a redox reaction; C is oxidised and O is reduced

Example:

NaHCO₃  + HCl  CO₂ + H₂O + NaCl

Na: +1 left; +1 right
H: +1 left (in bicarbonate) and +1 left (in HCl); +1 right
C: +4 left; +4 right
O: -2 left; -2 right (in CO₂) and -2 right (in water)
Cl: -1 left; -1 right

Conclusion: No change in oxidation states, therefore not a redox reaction.

Try playing the same game with the reaction of sulfur trioxide and water you posted. Is it a redox reaction? 

[confusedstud]

The SO₃ reaction is non redox as there is no change in oxidation states. However, I still can't explain which reagent is the Lewis acid or base. I'm not sure how the lone pair is transferred from the water to the sulfur trioxide molecule.

Thanks for the help