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Conversion facts

What is the conversion facts from grams to moles?

1 mole of a substance, has a mass equal to the relative mass of the substance.

Example:

1 mole of hydrogen gas ( $H_2$ ) has a mass of 2g
1 mole of hydrogen atoms ( $H$ ) has a mass of 1g
1 mole of chlorine atoms ( $Cl$ ) has a mass of 35.5g (relative atomic mass of chlorine = 35.5)

3 moles of oxygen gas ( $O_2$ ) have a mass of (3*16*2) = 96g

Ok? :)

Do you mean that it is the nuber of moles times the relative atomic mass times the sunscript?
Then 5 moles of helium gas is 40g

I do not know how that happened.

Quote:

Originally Posted by mathwiz3502

Do you mean that it is the number of moles times the relative atomic mass times the subscript?
Then 5 moles of helium gas is 40g

I'm not sure how you figured that 5 moles of He gas weighs 40 grams. I think you almost have the idea, but Helium is monoatomic (only one atom in the molecule). The subscript in a formula indicates the number of atoms of the element in the formula. Since Helium is simply "He", and it has an atomic mass of 4, then 5 moles of helium weights 20 grams. You figure out the molecular weight (the weight of 1 mole of the molecule from the atomic weight) and then multiply by the number of moles that you have to figure out the total weight.

Helium - Wikipedia, the free encyclopedia

Hydrogen, and a number of other pure gases are diatomic (two atoms per molecule).

$H_2,\, O_2,\, N_2$ are examples of diatomic molecules -- one molecule contains two atoms.

Hydrogen has an atomic mass of 1. it is diatomic. Its molecular weight is 2.
Oxygen has an atomic mass of 16. It is diatomic. Its molecular weight is 32
Nitrogen has an atomic mass of 14. It is diatomic. Its molecular weight is 28.

Helium has an atomic mass of 4. It is monoatomic. Its molecular weight is 4.
Neon has an atomic mass of 20. It is monoatomic. Its molecular weight is 20.
etc.