Chemistry 2006/ 2007 Club*** - page 15

I am starting Chem II this semester. Anyone want to start a club??? :rolleyes:... Read More

  1. by   AmericanChai
    I just wanted to share that Wikipedia.com is awesome for chem students! You can type in any chemical and it will give you the formula and characteristics of it. We are doing a lab on conductivity tonight and there were several pre-lab questions I didn't know how to answer because I was not familiar with the chemicals. After looking them up on Wikipedia I was able to easily answer the questions.

    Also use it when working on nomenclature problems. You can type in the name or the formula and Wikipedia will tell you if you have it right or not. Google works if you can't find it on Wikipedia.
  2. by   MedSurgRNiowa
    Thanks for the wikipedia referral. I am taking Chemistry this semester and I find it so boring. I am usually very studious but I find other things to do than study. My class is at 2 PM and the instructor is nice but very monotone so I struggle to stay awake. Anatomy was a breeze in comparison. This instructor wants everyone to succeed and offers help all the time which is fortunate after reading some of the other posts. I need to get into gear! :wink2:
  3. by   abrainerd
    Does anyone have a good way to memorize the polyatomic ions?? I know we just have to memorize, but a lot of them just don't seem to have a resemblence to what they are? Any suggestions would be appreciated.
  4. by   catzy5
    I just made flash cards and did them did them over and over again. I tried to memorize in like groups of charges as that is the big thing about them. I took one afternoon made cards and went over and over them. Now for this last test polyatomics were last unit but I found on some of my assignments that things that I messed up on were the polyatomic ions and some of the transitional metals when i was say writing and balancing equations so I highly recomend once you do know them to keep practicing them.
  5. by   catzy5
    Quote from rasberrikiss
    I have two problems I am stuck on! If anyone can, please help!

    1. The three main components of dry air and the percentage of each are N2 (78.08%), O2 (20.95%), and Ar (0.93%). Calculate the mass of one mole of air.

    2. The density of liquid octane, C8H18 is 0.7025g/mL. if 1.00mL of liquid octane is vaporized at 100 degrees Celsius and 725 torr, what volme does the vapor occupy?

    Thanks

    I was trying to reply to this, this morning but my password wasn't working, anyway I am not real sure on what to do on this other then adding them all up and wouldn't that be the mass of the total? or would you have to change all of them to mols first then calculate individual mass and add them up together?.


    The second question I have no clue sorry LOL but I am waiting anxiously to see a result if you find out before anyone posts please come back and tell us.
  6. by   romansten9
    Hello all,

    This is my first post in here, glad to see a club for this...I'm trying to keep a positive attitude about this chemistry stuff. Whenever I get bored I look for something interesting or find some "real world application" for this. It makes a big difference in attitude. I figure that I might as well find a way to enjoy this.

    One of the most interesting websites I've found is for a guy thats way more pumped up about elements than me, but his enthusiam rubs off. He actually built a periodic table table (not a misprint) Its a wooden table with actual elements inside. Its pretty incredible, and the website has tons of pictures, some experiments, links, etc.
    http://www.theodoregray.com/PeriodicTable/ Click on a wooden "tile" for an element and you will find out more than you ever wanted to know about that element, pretty amazing.

    My instructor helps keep it interesting. He works in a crimelab (I used to do autopsies, so I can relate) and he tells stories about cases and trials he testifies in..etc. to lighten up the class a bit.
    Last edit by romansten9 on Sep 29, '06
  7. by   romansten9
    I was going to also mention a couple of books that have helped me a LOT. I got them from my local library. everyone has heard of the "idiot" books (I qualify for them) Anyway, I like the "Complete idiot guide to chemistry" (orange book) a little more than the "Chemistry for dummies" (yellow book) but both are good. I think my favorite book is "The cartoon guide to chemistry" by Larry Gonick & Craig Criddle. (its on Amazon new or used) If you can't understand the cartoon book, I'll pray for you! We might as well make this class fun...
  8. by   romansten9
    To memorize anything you can use a mnemonic (or make your own) just do a search for "chemistry mnemonics" or check these out: http://www.xs4all.nl/~jcdverha/scijo....html#subindex
    http://www.medicalmnemonics.com/
  9. by   HARRN2b
    .7025=1/v

    I set up the chemical equation for the problem presented. I do not know where torr or 100 degree C fit into the picture (or if the even matter, as they may not). Density is mass divided by volume. I have not seen an equation that mentions torr or temp. That may not be necessary. Let us know.
  10. by   HARRN2b
    As far as the dry air, I would think one would need to calculate the molecular weight of N2, O2 and AR. Then percentage wise what do they equate. At least that is how I would calculate it. I have to go to work, otherwise I would go get the periodic table and calculate it out. Just figure out the molecular weight. For example 1 mol of H equals 1.01. Then take 78% of that. Do you follow?
  11. by   romansten9
    I don't know the answer to the density question, we aren't to that point in our text book. But I do know that temperature is going to change the density. I would suggest if we are going to tutor each other, that we don't "guess" This stuff can be confusing enough! So make sure you know what you're doing if you attempt to help someone else, or you'll confuse them worse! thanks! : )
  12. by   bon jovi
    ok...Hello all... I have little problem...I have to use heat of fusion, SH of water, and/or heat of vaporization...

    a) cal need to melt 50.0g of ice at 0C and to warm liquid to 65C (need 2 steps for this)

    this is what i thought i should do...

    I need for 1g H2O-80 cal.
    80cal/1g h2o * 50.0g = 4000 cal
    then : (65C*50g)*1.00cal/gC=3250cal
    4000+3250=7250 cal...

    however, resolt in the book gives me 7300 cal...What I am doing wrong?:uhoh21:
    also

    kJ given off when 15g of steam condenses at 100C and the liquid cools to 0C
    g*540cal/g=15*540=8100cal = 33.91 kJ

    result in the book is 40kJ...again what I am doing wrong? Please HELP....

    thanks

    Bon Jovi:Melody:
  13. by   abrainerd
    bon jovi, you ARE doing these correctly, you just are not remembering to round off to the significant figure. 7250 rounds off to 7300 and 33.91 would round off to 40kj. Your answers are correct.

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