Please help! question: the most accurate balance we currently have can measure to an error of +-10^-8 g. what is the error in terms of iron atoms?

Question

adamconner · Answer

we* @chmvijay

chmvijay · Answer

i am not getting the meaning of ur question have u written it properly without leaving anything

chmvijay · Answer

have can measure to an error  ?

adamconner · Answer

idk thats what the question says.

aaronq · Answer

Convert $1*10^{-8} g  $ to atoms of Iron.

first find moles, $n=\dfrac{m}{M}$, then find number of atoms, $N=N_A*n$.

then express it as  "$\pm$ x Fe atoms".

adamconner · Answer

ok, i dont know how to do the conversion. And for the moles: n=m/55.85. for m do i use the 1x10^-8?

aaronq · Answer

yep, m means mass.  $N_A$ is avogadros number, btw.

adamconner · Answer

ok, so n=.017x10^-8 and N=1.078x1-^15??

aaronq · Answer

N is the number of atoms, it cannot be less than 1

adamconner · Answer

can i do 1.078 x10^14

aaronq · Answer

yeah that's right

adamconner · Answer

ok, is that it?

aaronq · Answer

chyes

adamconner · Answer

ok, what did u mean about expressing as +- Fe atoms? or that what i just did?

aaronq · Answer

we'll the point of the question was to convert the mass given to atoms of iron, the calculations you did a second ago, did just that.

now as your final answer you should express the error in terms of Fe atoms.

          "+\- 1.078 x10^14 Fe atoms"

adamconner · Answer

ooh ok. i got confused on the +-part. well thanks so much :)

aaronq · Answer

no problem, dude.

the +\-  is actually $\pm$, which is used to express uncertainties in measurements. It literally means that the measurement is within a range.
e.g. 1 $\pm$ 0.1 meters, the value is definititly between 0.9 m and 1.1 m.

adamconner · Answer

ahh i see