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Ineed help with Chemistry

Discussion in 'Off Topic [BG]' started by unclejam, Aug 30, 2007.


  1. Jared Lash

    Jared Lash Born under punches Supporting Member

    Aug 21, 2006
    Northern California
    I don't want to seem rude, but I'm not sure I understand why you need help. There is reading preceding most of those questions that adequately explains how to answer them.

    Maybe if you gave a specific problem that you were having trouble with and why it would be easier to help you. It looks like the whole assignment is based around polyatomic ions and nomenclature, so it really isn't too difficult.
     
  2. I just don't get it

    I can't wrap my brain around it all
     
  3. Tony G

    Tony G

    Jan 20, 2006
    NY
    The best advice I ever got if I get stuck on a problem is to move on to something else, take a break, or whatever just to get it out of you mind for a little while. Then, when you are fresh, come back to it and see if you can comprehend the second time around.
     
  4. According to the link, it isn't due until September 12, so don't worry about it until the 11th.
     
  5. It's a big assignment, Pre-AP Chem, sections 6 onwards, yeah?
    You understand the ion list?
     
  6. This is something that would take too long to explain for every section, but I'll try to get you started. Take Section 6:

    Section 6 explains naming conventions for ionic compounds with a cation capable of two and only two valence states. These metal cations include Fe, Cu, Hg, Sn, and Cr (among others). For metals with more than two valence states, Section 6 does not generally apply.

    All Section 6 says is that the lower of the two valences takes the suffix -ous, and the larger of the valences takes the suffix -ic. The corresponding anion always takes the suffix -ide.

    Example: Iron (Fe) has two valences: +2 and +3. If the Fe is in a +2 state, it's Ferrous, and if +3, Ferric. If you recall that Oxygen and Sulfur anions are virtually always -2, and halogens are always -1, then any iron compound in Section 6 can be easily named.

    FeO - Oxygen is always -2, so Fe has to be +2 to keep neutral charge. Therefore, this compound is Ferrous Oxide.

    Fe[SUB]2[/SUB]O[SUB]3[/SUB] - Oxygen is -2 and there are three of them, so the negative charge is -6 (-2 x 3). Therefore the positive charge needs to be +6. If there are two irons, then each has to be worth +3. Therefore, Ferric Oxide.

    FeCl[SUB]2[/SUB] - Halogens are -1, so the total negative charge is -2, therefore the Fe is +2. Name: Ferrous Chloride

    All other problems are analogous. It's just a matter of determining what the two valence states for each metal are. Those values are available in the study materials (not necessarily Section 6). If you find those values, this assignment should be straightforward. The other sections are very similar as well.

    Hope this helps.
     
  7. BassyBill

    BassyBill The smooth moderator... Gold Supporting Member

    Mar 12, 2005
    West Midlands UK
    Wow. I didn't think anyone used those old names like ferrous and cupric any more. I'm kind of suprised to find them in a school assignment.
     
  8. Poop-Loops

    Poop-Loops Banned

    Mar 3, 2006
    Auburn, Washington
    I never had to memorize them, but it was "optional" when I took chem a year or so ago in college.

    The thing that put me off from chemistry was all the naming and memorization. =/
     
  9. Step 1: Pay some smart kid 20 bucks to do it for you and work a couple hours overtime to pay for it.
    Step 2: Repeat.
    Step 3: Profit!

    Just make sure you actually learn and practice the things you are learning along the way so that you can actually do decent on tests. Other than that, enjoy the fact that you paid for great marks on assignments that are done flawlessly and get you great marks.
     
  10. I am too.
    I didn't even need to learn them like that for 1st year chemistry at uni, but some you just get used to and know them anyway. I never knew the rules to naming them, and tbh didn't need to. Molecular bonding is important to understand however, and hope unclejam looks for more help to understand if it's not making sense.
     
  11. When I took chem it was really old school..... acqua regia, spirit of salt, mercury of life, aurum and cinnabar :eek:
     
  12. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    Agreed. We were taught them for our benefit, but not tested on them - it's good to know (and not hard to remember anyway) for those times when you find an old bottle of something.

    The IUPAC naming standard for ionic compounds like those would be, using oxides of iron as an example:
    FeO, Iron (II) Oxide
    Fe[SUB]2[/SUB]O[SUB]3[/SUB], Iron (III) Oxide
     
  13. AdlerAugen

    AdlerAugen

    Aug 9, 2006
    bleh we all do. Especially in my freshman honors chemistry lab...we're using a lab manual more geared toward college seniors than freshman general chem. No one knew what to do as far as this one compound synthesis today.
     
  14. You kids... making me feel old. :scowl:

    When I was in AP (a quarter century or so ago), you still ordered many chemicals using the traditional names. "Iron (II) Oxide" wasn't even in the catalog. You'd have been laughed at for using the term "2-propanol" instead of "isopropyl alcohol."

    You forgot "phlogistin" and "the ether"... :D
     
  15. hbarcat

    hbarcat Supporting Member

    Aug 24, 2006
    Rochelle, Illinois



    Oh yeah? Well, I can top that! I took chemistry in school so long ago that we only had four elements to learn: Air, Earth, Water and Fire.




    :D
     
  16. millahh

    millahh Supporting Member

    Sep 20, 2005
    Hoboken
    Believe it or not, the aqua regia is still a phrase in common use, at least amongst the folks who do trace-metals analysis.

    As far as the other non-IUPAC nomenclature, it is useful to know once you're outside of a classroom setting, as different people are used to using different naming systems. For example, I see all four of isopropanol, isopropyl alcohol, 2-propanol, and IpOH used frequently. Alot of non-IUPAC names have become part of the "culture" (particularly for organic molecules), and aren't going anywhere. Some of the more confusing ones (those that indicate oxidation states of the metal) seem to be falling into disuse, though.
     
  17. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    Indeed - I worked in a lab doing that for a summer, that term was very commonly used.

    This mirrors my experience too. I'm usually big on the IUPAC names, but sometimes they can be the least common. One time I was doing an inventory of solvents and I came across a box of "2-propanol". I stared at it for about 5 minutes before I realized I was looking at isopropanol/isopropyl alcohol :D

    Organic molecules, due to the fact that there are so many, have adapted informal names into IUPAC, using formal prefixes and suffixes on base words from the old nomenclature, and vice versa. You get used to it pretty quick, but it does make organic nomenclature more complicated.
     
  18. In the Army lab where I work, we call it IPA. The first time I walked into brewpub and the server asked if I "... would like to try a pint of IPA" it didn't register, and I kind of looked at her funny. I think she thought I had gas or something. :p
     
  19. millahh

    millahh Supporting Member

    Sep 20, 2005
    Hoboken
    Yeah, I forgot about that one. And I had a similar reaction the first time I saw IPA on a menu as well.

    If I may ask, at what lab do you work? I'm doing the pharma thing at the moment, but definitely have my eye on working at a govt lab further down the road.
     

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