How many moles are in #"1.68 g Fe"#?

1 Answer
Jul 25, 2017

Answer:

There is #"0.0301 mol Fe"# in #"1.68 g Fe"#.

There are #1.81xx10^22# atoms in #"1.68 g Fe"#.

Explanation:

Divide the mass of iron by its molar mass in g/mol to get the moles of iron.

#(1.68color(red)cancel(color(black)("g Fe")))/(55.845color(red)cancel(color(black)("g Fe"))/"mol Fe")="0.0301 mol Fe"#

One mole of anything is #6.022xx10^23# of anything, including atoms. Multiply mol Fe by #(6.022xx10^23)/("mol")#.

#0.0301color(red)cancel(color(black)("mol Fe"))xx(6.022xx10^23"atoms Fe")/(1color(red)cancel(color(black)("mol Fe")))=1.81xx10^22 "atoms Fe"# (rounded to three sig figs)