[Sprinkles]

For the following reaction
BaS(s) + 2O2(g) → BaSO4(s)
How many electrons are being transferred?

What is the clearest way to explain how to count how many electrons are being transferred? I know the answer is 8. Any help would be so GREAT! Thank you!

[rabolisk]

The clearest way is to balance the reaction using the half-reaction method, and showing that 8 electrons are involved. One easy, intuitive way is to see that there are 4 oxygen atoms in the reaction. Their initial oxidation state is 0, and their final oxidation state is -2, thus 4 * 2 = 8 electrons must have been transferred to oxygen.