quick chem question |
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 Nov 30 2008, 08:03 PM
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#1
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 Senior Member  Group: Staff Alumni Posts: 2,454 Joined: Nov 2008 Member No: 696,018  |
I must be too tired or something. Seriously. I'm going through old chem quizzes to review for the cumulative exam. On the very first quiz, I got one question wrong and I can't seem to figure it out. I'd email my TA, but he most likely wont get back to me on time.
Anyways, it's a standard (C1)(V1) = (C2)(V2) equation. You're preparing a diluted solution: 200 mL of .096 M solution. Your stock solution is 1.6 M (error +/- 0.1). The pipette available is 10.0 +/- 0.1 mL. What's the volume of stock solution needed? So it's basically (.096 M)(200 mL) = (1.6 M)(x volume of stock solution needed) Right? Am I completely blanking out? Because when I solve for that, I'm getting 12.0 +/- 0.2 mL needed and the correct answer is supposed to be 15.0 +/- 0.2 mL. 
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Nov 30 2008, 09:16 PM
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#2
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 Drank wit your boy Group: Official Member Posts: 1,711 Joined: May 2008 Member No: 649,997 |
WTF
WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF |
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Nov 30 2008, 10:55 PM
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#3
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Senior Member Group: Staff Alumni Posts: 2,454 Joined: Nov 2008 Member No: 696,018 |
i'm gonna get my ass handed to me tomorrow. |
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Nov 30 2008, 11:13 PM
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#4
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 Live long and prosper. Group: Staff Alumni Posts: 5,525 Joined: Nov 2006 Member No: 478,024 |
QUOTE(BanDaSnowman @ Nov 30 2008, 08:16 PM)  WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF That is why i took all forms of Bio durring high school.f*ck that |
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| *Janette* |
Nov 30 2008, 11:17 PM
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#5
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Guest |
Wait, wouldn't 1.6 M be your initial concentration since it's the stock you start out with? And .096M = C2 since it's what you're preparing?
I don't know, I've been doing a paper for 8 hours. I could be wrong. |
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Nov 30 2008, 11:18 PM
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#6
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Senior Member Group: Staff Alumni Posts: 2,454 Joined: Nov 2008 Member No: 696,018 |
yeah. doesn't really make a difference, though. c1v1=c2v2 is the same as c2v2=c1v1.
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| *cakedout* |
Nov 30 2008, 11:21 PM
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#7
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Guest |
i got lost at stock solution
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Dec 1 2008, 12:40 PM
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#8
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Senior Member Group: Staff Alumni Posts: 2,454 Joined: Nov 2008 Member No: 696,018 |
hehe I figured it out. Apparently, we're making 200mL solution, but we're using a 250mL volumetric flask (which I left out of the original post bc I didn't think it was important, lol), which only has one line at the 250 mark. So I was supposed to use "250" for v2 instead of "200." I love my roommate.
Arright, this can be closed, etc. |
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Dec 1 2008, 03:39 PM
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#9
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 Senior Member Group: Staff Alumni Posts: 3,645 Joined: Feb 2004 Member No: 4,975 |
WTF indeed.
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Dec 1 2008, 04:19 PM
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#10
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 Senior Member Group: Member Posts: 70 Joined: Aug 2008 Member No: 680,835 |
QUOTE(BanDaSnowman @ Nov 30 2008, 10:16 PM) WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF WTF agreeed i got lost in the first word |
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Dec 1 2008, 04:20 PM
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#11
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Senior Member Group: Member Posts: 70 Joined: Aug 2008 Member No: 680,835 |
QUOTE(heartquasm @ Dec 1 2008, 01:40 PM) hehe I figured it out. Apparently, we're making 200mL solution, but we're using a 250mL volumetric flask (which I left out of the original post bc I didn't think it was important, lol), which only has one line at the 250 mark. So I was supposed to use "250" for v2 instead of "200." I love my roommate. Arright, this can be closed, etc. well at least u got it withought our help i think |
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Dec 1 2008, 04:23 PM
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#12
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Senior Member Group: Staff Alumni Posts: 3,645 Joined: Feb 2004 Member No: 4,975 |
wtf don't double post
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Dec 1 2008, 04:25 PM
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#13
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 L!ckitySplit Group: Member Posts: 4,325 Joined: Apr 2005 Member No: 129,329 |
you lost me at "chem"
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Dec 1 2008, 04:26 PM
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#14
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Senior Member Group: Staff Alumni Posts: 3,645 Joined: Feb 2004 Member No: 4,975 |
You lost me at quick.
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Dec 1 2008, 04:29 PM
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#15
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L!ckitySplit Group: Member Posts: 4,325 Joined: Apr 2005 Member No: 129,329 |
but you had me at hello :)
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