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View Full Version : A 0.0113 mol sample of urea, NH2CONH2 contains how many atoms?


sky333blue
Feb 15, 2010, 06:24 AM
I'm having trouble getting the correct answer to this question which is 5.44 x 10e22 atoms. I've figured the problem just about every way with Avagadro's number and still can't get the right answer. I was wondering if anyone can help me figure out how to set this problem up so that I can understand how to solve to problem correctly? Thanks for all your help in advance! : )

Unknown008
Feb 16, 2010, 11:44 AM
Well, start like this:

1 molecule of urea contains = 8 atoms.
So 1 mole of urea will contain 8 moles of atoms.
This means that 0.0113 moles of urea contains 8*0.0113 moles of atoms, making 0.0904 mol of atoms.

Since 1 mol = 6.02 x 10^23
0.0904 mol = 6.02 x 10^23 * 0.0904 = 5.44 x 10^22

I hope it helped! :)

sky333blue
Feb 16, 2010, 01:42 PM
You're an AMAZING HELP!! Thank you SO much!! I really appreciate it! Can I ask you one more question though... how'd you know that 1 mol of urea had 8 atoms in it? That's where I was hung up and didn't know how to figure out.

Unknown008
Feb 16, 2010, 06:46 PM
You simply count up them.

Urea: NH2CONH2: 2 N atoms, 4 H atoms, 1 C atom, 1 O atom :)

sky333blue
Feb 17, 2010, 10:01 AM
WOW! Do I feel like an idiot or what? LMAO!! Thanks again for all your help! Sometimes its just understanding the most minute aspect of the problem to figure out how everything works. : )

Unknown008
Feb 17, 2010, 10:18 AM
You're welcome lol :)