Avogardro's number? I have to calculate the cost in dollars of a single aluminum atom in the roll of aluminum foil. The only information i received was: the roll (on scale) cost $1.75. The weight of aluminum in the roll is 300 grams. I have no idea how to figure this out, please help!

Question

aaronq · Answer

first convert 300 grams of Al to moles of Al.

anonymous · Answer

so that would be 26.982/300, right? That would come out to 0.08994 moles

aaronq · Answer

no it's the other way around, $n=\dfrac{m}{M}$

anonymous · Answer

okay, then it would come out to 11.119

aaronq · Answer

so you have 11.119 moles

next you wanna find out many atoms there are in the roll of foil

$n=\dfrac{N}{N_A}$

N=atoms, $N_A$=avogadros number, n= moles

anonymous · Answer

so 11.119/6.02*10^23?

aaronq · Answer

nope. n=moles=11.119

aaronq · Answer

$11.119\;moles=\dfrac{N}{6.022*10^{23}}$

anonymous · Answer

so to solve that would I just cross multiply or is it not that easy?

aaronq · Answer

yep. it's just algebra

anonymous · Answer

and then (6.022*10^23)*11.119 would be 6.693638 *10 ^24

aaronq · Answer

so that's how many atoms you have, do you know what do after?

anonymous · Answer

I'm not sure how to figure out the price of an atom now.. If the cost is $1.75 would I just divide the 6.69..ect number from that?

aaronq · Answer

yep. just like if  10 jet skies costed $10, and you wanted to find out how much each would cost.

anonymous · Answer

ok, thank you so much for all your help!

aaronq · Answer

no problem dude!