Methredel - 22-9-2013 at 02:47
Hey everbody,
I have question ,this is not a question of a textbook ,but the answer will/would really help me to solve my problems (ha problem solving -any
jokes?):
What are the oxidation states of Carbon , Hydogen and Oxygen in C2H5OH (Ethanol)?
Thanks for the answer and have a nice day 
confused - 22-9-2013 at 03:10
C2H5OH has an oxidation state of 0
O= -2
H= +1
C= +2
i think...hope that my calculations are correct
Methredel - 22-9-2013 at 03:47
Somehow this cant be correct or our teacher just lied to us about the oxidation state stuff
Hasnt the hydogen in the middle not in the hydroxid group a oxidation state of -1 . And the carbon the state of +3 ? Am i wrong?
Thanks for your answer .
confused - 22-9-2013 at 04:01
the OH group is -1 because O=-2 and H= +1
so i dont think thats the problem, just added up the oxidation numbers of the ions
i might have made a mistake at the oxidation state of carbon, i think it might be that the C attached to the hydrogens is +3 while the carbon attached
to the OH group has a -1 oxidation number
Methredel - 22-9-2013 at 04:03
oh ok thanks . Maybe i dont have t do this exercise , because this is the year where we learn the "basics of organic chemistry" . I´ll try it anyway
Marvin - 22-9-2013 at 04:35
Try using the usual method first. The sum of oxidation states must add up to the charge on the molecule. Start with the elements you know, in their
standard oxidation state and solve for the element you don't know.
Methredel - 23-9-2013 at 06:22
Ok i got it right ,we correct it today .Thanks for your answers
woelen - 23-9-2013 at 23:30
Usually, oxygen is -2, hydrogen is +1 (except in metal hydrides, where it is -1).
I would say, the C at the CH3-part of the molecule has oxidation state -3 and the C at the CH2(OH) part of the molecule has oxidation state -1.
C-C bonds do not contribute to oxidation state (increase or decrease of 0). If you use that info, then the numbers, given above, follow from simple
math.
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In general, the concept of oxidation state is not as easy as it seems for somewhat more complicated molecules or ions and sometimes it even is
possible to assign different oxidation states to atoms and still be correct. The problem is especially hard when atoms of the same element are
connected to each other, as usually is the case in organic compounds. A nice example of ambiguous oxidation states is the thiosulfate ion, S2O3(2-).
This ion has a structure with a central S-atom, to which three O-atoms and a single S-atom are connected. It actually is a sulfate ion, with one
O-atom replaced by an S-atom.
Oxidation state of oxygen is -2, the total charge is -2, which leaves for the sum of the oxidation states of the sulphur atoms a value of +4. Some
people say the central atom has oxidation state +6 (just as in normal sulfate ion) and the other sulphur atom has oxidation state -2. Other people say
the central atom has oxidation state +4 and the other sulphur atom has oxidation state 0. The latter values are because one can see thiosulfate ion as
a sulfite ion (which has sulphur in oxidation state +4), to which elemental sulphur is added (this actually is a well-known method of production of
thiosulfate, boiling a solution of Na2SO3 with powdered sulphur). Which view is correct? There is no answer to this, oxidation state is just a
bookkeeping device and both views seem equally valid.