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Topic: number of atoms in 5.86 mg Be  (Read 1908 times)

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Offline olivier

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number of atoms in 5.86 mg Be
« on: August 06, 2012, 08:57:45 AM »
Hi all,
first question: what is the number of atoms in 5.86 mg of Be?
5.86 mg = 0.00586 g
1 mole Be = 9.012 g

so we have here: 0.0006502 mole of Be. When I multiply this with 6.022 x 10^23
I get 3.92  x 10^20

The answer in the book is 3.92 x 10^17 What am I doing wrong?
Thanks in advance for answering...
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Offline Dan

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Re: number of atoms in 5.86 mg Be
« Reply #1 on: August 06, 2012, 09:43:47 AM »
Are you sure the book says mg (milligrams) and not mg (micrograms)?

If it's 5.86 mg, I agree with your answer.

The answer given in the book is the number of atoms in 5.86 mg of Be.
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Offline olivier

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Re: number of atoms in 5.86 mg Be
« Reply #2 on: August 06, 2012, 10:16:43 AM »
Thanks for your answer. The book does say mg instead of μg, so it has to be an error in the book.
Anyway, I'm glad that I can ask here, because I'm a complete newcomer in chemistry.
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