Question

What result do you get when you multiply the number of moles of a sample by the following conversion factor? (g of element)`/`(1 element)

Answer 1

I think you mean to multiply the mass of an element by `1/("molar mass of the element")`

Explanation:

And if we do this we get:

`"mass of the element (g)"/("molar mass of the element"(g*mol^-1))`, we get an answer in `"moles"`, because, `g/(g*mol^-1)=cancelg/(cancelg*mol^-1)=1/(1/(mol^-1))=mol` as required.

So if I have `12*g` of carbon, I have a molar quantity of `(12*cancelg)/(12.011*cancelg*mol^-1)~=1*mol`.

The quotient gives an answer in `"moles"` dimensionally.

From where do I get the molar masses? Have I memorized them? Do you have to memorize them for an exam?

Actually, you will memorize the more common molar masses, i.e. those of oxygen, nitrogen, carbon, sodium, iron...........