How would you do the math for the number of atoms in a sample of 135 mg of selenium? - sample of welcomepeech
I am working on my homework and I think that the chemistry to calculate the number of atoms in a sample of 135 mg of selenium ... How do I do that math for that?
Thursday, February 18, 2010
Sample Of Welcomepeech How Would You Do The Math For The Number Of Atoms In A Sample Of 135 Mg Of Selenium?
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3 comments:
135/the mass of the atom (in mg) = amount.
I'm not sure what selenium is difficult, but ... But it will help a bit:)
And BTW, this is just another shower .... made me facepalm: P
1 - It is necessary to work with SI units for work ... 135mg = 0.135g
2 - You also need the MM (molecular weight) of selenium, 78.96 (, g / mol)
3-1 mol = 6.02x10 ^ 23 particles (atoms or molecules in the subject matter). In this case atoms.
4 - Now you have everything you need:
0.135g • IS 1mol · Se/78.96g is 6.02x10 ^ 23 atoms / 1 mol
5-You and operations units of the cross and the answer would be:
1.03x10 ^ 21 (which makes sense because it is much less than 135 mg per mole)
Find the atomic weight of selenium, lord of the mass of Avogadro number of atoms of selenium, 6.02 23. x 10 ^
Therefore, 135 / M = n / (6.02 x 10 ^ 23)
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