delco714 Posted September 17, 2008 Share Posted September 17, 2008 I sit here, trying to do a dry lab, never took chem before, and now I'm premed in College... awesome.. so as the other students seem to have a nice grasp b/c this took this course in HS already (or failed once before), I'm stuck with the assumption that I should "know" this already, and I'm far from understanding it.. My lab has questions such as this: "indicate the oxidation number of carbon and sulfur following the compounds" a) Na2C2O4 b) SO2 ...etc.. is this right?.. Na has +1 oxid#, and there's 2, so it's 2+; O4 is 2-, there's 4 of them so.. 8-.. 8- + 2+ = 6-... there's 2 Carbon.. so each carbon must = 3+ to balance this...i have no idea what I'm doing.. i'm just trying to figure it out.... and for SO2.. oxygen is a peroxide.. so it's 1-...but S never has a charge of 1+ according to the PToElements... WTF.. if you can help.. thanks a mil. Link to comment Share on other sites More sharing options...
Cap'n Refsmmat Posted September 17, 2008 Share Posted September 17, 2008 You've the first one right, but for the second, peroxide has a -2 charge, not a -1 charge. (You'd get that number from a table of polyatomic ions.) Link to comment Share on other sites More sharing options...
delco714 Posted September 17, 2008 Author Share Posted September 17, 2008 waitttt.. SO2 is a peroxide... so it is 2-... but only 1- when paired with H (H2O2 >>hydrogen peroxide).. is that right? ..so if it is 2-.. than the S will be 2+ to balance? Link to comment Share on other sites More sharing options...
Cap'n Refsmmat Posted September 17, 2008 Share Posted September 17, 2008 It's still 2- when paired with hydrogen peroxide. Each H in [ce]H2O2[/ce] has a 1+ charge, for a total of 2+. The peroxide balances it out with 2-. And yes, the S would be 2+. Link to comment Share on other sites More sharing options...
delco714 Posted September 17, 2008 Author Share Posted September 17, 2008 shweeet.. im getting the hang of it.. thanks for the help. Link to comment Share on other sites More sharing options...
jdurg Posted September 18, 2008 Share Posted September 18, 2008 SO2 is NOT a peroxide! A peroxide is a species where the O-O bond exists. Thereby each oxygen has a single bond to the other oxygen. In SO2, the oxygens are bound to the sulfur atom, and each oxygen has an oxidation number of -2. So the S in SO2 has an oxidation number of +4. (SO2 is a structure like H2O where the O is in the middle with two hydrogens attached. In SO2, the S is in the middle with the two oxygens attached). Whenever you do oxidation numbers, it is CRUCIAL to know the structure of the compound you're looking at. Link to comment Share on other sites More sharing options...
Cap'n Refsmmat Posted September 18, 2008 Share Posted September 18, 2008 Crap. I take it I should have gotten the hint from that being a covalently, and not ionically, bonded molecule? Link to comment Share on other sites More sharing options...
delco714 Posted September 18, 2008 Author Share Posted September 18, 2008 jdurg, awesome point, you're right.. S2O2 would be a peroxide right? And yes, it's covalent, that much i know! 2 Non-Metals! Link to comment Share on other sites More sharing options...
big314mp Posted September 18, 2008 Share Posted September 18, 2008 I would think that it would be a structure similar to SO3, with one oxygen swapped for a sulfur. I don't think that compound exists though. Link to comment Share on other sites More sharing options...
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