What is the quantity in moles of iron atoms do you have if you have 3.40*10^23 atoms of iron. (The mass of one mole of iron is 55.85g.)

Answer 1

to Answer this question we need to understand the unit of measurement, “mole.”

A mole can be thought of like “a dozen”

you can have a dozen of ANYTHING and it means there are 12 of those [things].

1 dozen [eggs] = 12 eggs

1 dozen [chickens] = 12 chickens

1 dozen [people] = 12 people

1 dozen [stars] = 12 stars

It doesn’t really matter how big it is, or even if it is realistic, if you say there’s a dozen [things], then you are saying there are 12 [things].

the “mole” is the same idea as a “dozen,” but the number of things that a mole represents is a phenomenally big number.

1 dozen [things] = 12 things

1 mole of [things] = 602,200,000,000,000,000,000,000 things

You may ask “how in the world am I supposed to remember that number?!”

Well, that is where scientific notation comes in handy!

1 mole = 6.022x10²³ things! (Pro Tip: memorize this number)

That number is so so so large that it really doesn’t apply to anything that we interact with in day to day life (unlike a dozen).

1 mole of eggs would fill up significantly more than the earth, so we don’t often use the mole for anything other than atoms.

And I hope that, once you understand the mole, you’ll have a better appreciation for the scale (how small) of atoms.

We are told we have 3.4x10²³ atoms of iron. 6.022x10²³ atoms would be a mole of atoms, but we only have 3.4x10²³, so we can be sure we have less than one mole of iron atoms.

(3.4x10²³ atoms Fe)(1 mole Fe/6.022x10²³ atoms Fe) = 0.56459647957 mole Fe

and because iron’s molar mass is 55.85 g / mole, that would mean we have ~31.53 grams of iron.