For most of last week, exhausted, weary, bummed out, generally feeling like total crap, I was pretty sure I would end up dropping a class this term. That would suck, cause I'd only have to take the same class again at a later time, much like the ill fated micro economics class of September 2004. Only, on Sunday, a miracle happened: Chemistry study group! And who formed this nerderiffic little club? I did! I did! I did! I spent Sunday afternoon sitting in the cafeteria at school with some of the other 'older' students in the class, going through chem notes, bitching about our prof, and actually absorbing the info. I went home and finished my prelab assignment and my lab write up, and actually figured stuff out on my own.
Here is what I can do:
An experiment calls for 10.0 grams of anhydrous copper(II) sulfate, but the only chemical available in the chemical supply room is copper(II) sulfate pentahydrate. How many grams of the hydrate would have to be heated to provide 10.0g of the anhydrate?
Reaction equation:
CuSO4.5H20(s) --heat--> CuSO4(s) + 5H2O(g)
hydrate anhydrate
Step 1 was figuring out that this was basically the same compound, and all I needed to do was separate the CuSO4 from the water to get the stuff I needed for the experiment. But how much? Well, to do that I need to figure out the percent composition of CuSO4 in the hydrate.
So . . .
% mass CuSO4 = 159.6096g CuSO4 / 249.686g CuSO45H2O x 100 = 63.9241%
then . . .
?g CuSO4.5H2O x 63.9241 / 100 = 10g CuSO4
and . . .
?g CuSO4.5H2O x 0.639241 /0.639241 = 10g CuSO4 /0.639241 = 15.6435g CuSO4.5H2O required
Lets double check that . . .
15.6435g CuSO4.5H2O x 63.9241g CuSO4 / 100g CuSO4.5H2O = 10g. CuSO4!!!!
Some of the cancellations may be a little unclear, but that's about me not being a computer genius, not anything to do with the chemistry.
Horrah! Chemistry study group rules! This makes me ridiculously happy, and I think I may survive the term after all!
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5 comments:
Oh my god.
I think my brain just exploded.
Good on you for figuring that out, KT :)
URAQTKT
XOHT
I wonder if my Home Ec teacher knew how to do that?
Baking Soda was the most chemical mystery I recall encountering in class...
Failed cooking. Got an A+ in sewing, along with threats of violence if I didn't help the class bully finish HER sewing project.
X.
Um...........HUH?
*blinks with confusion*
This is why I work with children and not chemicals.
I woke up thinking about my cousin today and it dawned on me that she has a friggin' blog. Perfect! I can tell her that I love and miss her and despite the lack of communication often think about her and wonder how she's doing.
I might as well continue talking about her in the 3rd person.
I hope she knows she's welcome in Montreal anytime! (I'm a much better hostess than correspondent)
I must also say that instead of admiring her beautiful boyfriend as I should, upon viewing the photo I was overwhelmed by psycho-protective thoughts and imagined how easy it would be to kill him if he ever hurt my precious cousin. I guess that's how I know we're family.
I LOVE YOU!
Katherine
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