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Topic: amount of atoms???  (Read 2689 times)

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Offline scottydsntknow

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amount of atoms???
« on: February 11, 2009, 01:52:14 AM »
How many total atoms are present in   34.4 g   of   PCl5


To enter an answer in scientific notation use   E   for the exponent

e.g.   6.022 x 1023   enter as   6.022E23


Enter a numeric answer only, do not enter units.

it keeps tellling me i have to answr wrong. i guess im using the 34.4 wrong
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Offline 2clients

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Re: amount of atoms???
« Reply #1 on: February 11, 2009, 02:17:43 AM »
1) Use the periodic table to determine the molar mass of PCL5.

2) Convert the mass into moles using the molar mass. 

3) Multiply the number of moles by avogrado's number.
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Offline macman104

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Re: amount of atoms???
« Reply #2 on: February 11, 2009, 06:11:45 PM »
Quote from: 2clients on February 11, 2009, 02:17:43 AM
1) Use the periodic table to determine the molar mass of PCL5.

2) Convert the mass into moles using the molar mass. 

3) Multiply the number of moles by avogrado's number.
You forgot a step, that will give you the number of molecules of PCl5 in the mass.  How many atoms are there in 1 PCl5 molecule?

scotty, please post how you solved the problem (include your math), and someone can help you from there.
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