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### Topic: Finding moles problem help?!  (Read 3040 times)

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#### xxhautecouture

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##### Finding moles problem help?!
« on: August 30, 2009, 07:31:05 PM »

Deutrium is an isoptope of hydrogen. The abundance of deutrium in water is 0.0150%. How many moles of water would be required to obtain .0790 moles of deutrium (D2)?

#### Fridushka

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##### Re: Finding moles problem help?!
« Reply #1 on: August 30, 2009, 07:54:42 PM »
writing the equation maybe might be helpful..

#### xxhautecouture

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##### Re: Finding moles problem help?!
« Reply #2 on: August 30, 2009, 07:56:42 PM »
ahh i've tried writing the equation... Do i use avogadro's number? Also, do i use the molar mass of H2O? Thanks again in advance, if someone could just guide me to the correct equation i would appreciate it!

#### bstapes99

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##### Re: Finding moles problem help?!
« Reply #3 on: August 31, 2009, 01:08:25 PM »
dude this is simple. Talk it out to get the equation. If I have X mol H20 times [Deuterium] (concentration = .0150%), I have X mol Deuterium (in this case .790 mol). Or,
X mol H20 x .000150 = .0790 mol Deuterium
The question asks for an answer in moles, so you never have to touch molar mass or Avogadro's number.