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Soverign1 · Sep 23, 2009, 07:53 PM

An atom of gold has a mass of 3.271x10-22g. How many atoms of gold are in 5.00 g of gold?:confused:

Perito · Sep 24, 2009, 05:29 AM

There is an Avogadro's number of atoms in 1 mole of any substance. That includes gold.

$mass\,\div\, \frac {mass}{mole} \,=\,moles$

The atomic weight is $\frac {mass}{moles}$ (usually grams/mole) so all you have to do is divide the mass by the atomic weight and you have the number of moles. To find the number of atoms, simply multiply the number of moles by Avogadro's number

$moles \,\times\, Avogadro's \,number \, = \, atoms$

Unknown008 · Sep 24, 2009, 10:01 AM

There isn't even need to use the Avogadro's constant here. This problem is only a proportion problem.

$3.271 \times 10^{-22}$ g -> 1 atom

1 g -> $\frac{1}{3.271 \times 10^{-22}}$ atom

5 g -> $\frac{1}{3.271 \times 10^{-22}} \times 5$ atoms

Perito · Sep 24, 2009, 11:00 AM

Quite right. I didn't read the problem completely.