Posted by **Justin** on Tuesday, January 1, 2008 at 1:21pm.

I'm having trouble converting moles to grams and finding the mass of molecules.

Problems I'm stuck on:

What is the mass in grams of .99x10^49 Sodium Chloride Molecules?

and How many moles of Cu are in 9.61 grams?

and How many moles are in 5.94x10^45 Ne atoms?

I just really need to know how to solve these. Thanks.

- Chemistry=MOLES! -
**drwls**, Tuesday, January 1, 2008 at 1:38pm
<<What is the mass in grams of 0.99x10^49 Sodium Chloride Molecules?>>

First find out how many moles that is by dividing by Avogadro's number, 6.02*10^23 molecules/mole. You get 1.64*10^25 moles. Then multiply that result by 58.5 gm/mole, the molar mass of NaCl.

You will get a very large number, comparable to the mass of the Earth. Are you sure you copied the problem correctly?

<<How many moles of Cu are in 9.61 grams?>>

Divide by the atomic mass of Cu, 63.5 g/mole

<<How many moles are in 5.94x10^45 Ne atoms?>>

Multiply that by the atomic mass of Neon, which it would be a good idea to look up, so that you get some practice doing this sort of thing.

- Chemistry=MOLES! -
**DrBob222**, Tuesday, January 1, 2008 at 1:40pm
The two pertinent pieces of information are here.

mols = grams/molar mass

There are 6.02 x 10^23 anythings in a mol; therefore,

mols = # atoms/6.02 x 10^23

or

mols = # molecules/6.02 x 10^23

Let me know if this doesn't help but explain in detail what the problem is.

- Chemistry=MOLES! -
**Damon**, Tuesday, January 1, 2008 at 1:42pm
Well, you know that twelve of anything is a dozen of them.

In exactly the same way, 6.022*10^23 of atoms or molecules is a mole of them.

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