Homey Posted June 22, 2017 Share Posted June 22, 2017 (edited) Hello, How would I go about finding the number of atoms in an element sample, given the density. I have found the volume and mass of my sample and presume I should work it like such: [Number of atoms] = [Avogadro's Number] * (density) * volume/(atomic weight) In my case, I have aluminum foil of 27g, 27g/mol, and 10 cm3 When using the equation above I end up with six atoms? I suppose the error is in the equation(but I don't know) Thanks Edited June 22, 2017 by Homey Link to comment Share on other sites More sharing options...
DrP Posted June 22, 2017 Share Posted June 22, 2017 Haven't done this for ages... but just a quick question... If it is 27g/mol and you have 27 grams of aluminium, then wouldn't that mean that you have 1 mol of aluminium and thus Avagadro's number of atoms? 1 Link to comment Share on other sites More sharing options...
swansont Posted June 22, 2017 Share Posted June 22, 2017 When using the equation above I end up with six atoms? What is Avogadro's number? 1 Link to comment Share on other sites More sharing options...
Homey Posted June 22, 2017 Author Share Posted June 22, 2017 Haven't done this for ages... but just a quick question... If it is 27g/mol and you have 27 grams of aluminium, then wouldn't that mean that you have 1 mol of aluminium and thus Avagadro's number of atoms? Yes that is what I got but I was a bit skeptical of it but thanks for the clarification Link to comment Share on other sites More sharing options...
DrP Posted June 22, 2017 Share Posted June 22, 2017 ah... thus the 6 atoms... I think it is about 6 x 10^24 or something like that. ;-) (Just looked it up - it's x10^23 - still huge though) 1 Link to comment Share on other sites More sharing options...
OldChemE Posted June 22, 2017 Share Posted June 22, 2017 Look at the units associated with Avogadro's number, and you should be able to write a much simpler equation that directly converts grams to atoms. When you have a problem involving different units of measure, you can use the units to determine the appropriate equation. Avogadro's number is atoms/mole, atomic weight is grams/mole, sample size is grams. How could you multiply or divide these three sets of units in order to have a result which is in units of atoms? Do this and you will have your answer. 1 Link to comment Share on other sites More sharing options...
Homey Posted June 22, 2017 Author Share Posted June 22, 2017 Look at the units associated with Avogadro's number, and you should be able to write a much simpler equation that directly converts grams to atoms. When you have a problem involving different units of measure, you can use the units to determine the appropriate equation. Avogadro's number is atoms/mole, atomic weight is grams/mole, sample size is grams. How could you multiply or divide these three sets of units in order to have a result which is in units of atoms? Do this and you will have your answer. Thanks, this seemed to be the most straightforward away about working my problem Link to comment Share on other sites More sharing options...
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