[Shea]

How many atoms of fluorine (F) are in 100g of fluorine gas (F2)?

100g of F2 / 38 grams of F2 per mole = 2.6moles

2.6 moles x 6.23 x 10^23 atoms per mole = 1.6198 x 10^24 atoms



How many moles of hydrogen are produced when 2.1 moles of magnesium are dropped into hydrochloric acid?

Mg + 2HCl -> MgCl2 + H2

1 mole of Mg makes 1 mole of H2

2.1 moles

How many moles of the HCl are used in the previous question?

2.1


Where did I mess up?

[Borek]

2.6 moles x 6.23 x 10^23 atoms per mole = 1.6198 x 10^24 atoms

That's not number of atoms. That's number of particles. How many atoms per particle?

How many moles of the HCl are used in the previous question?

2.1

How many moles of HCl react with 1 mole of magnesium? Look at the reaction equation.

[Shea]

I don't know how many atoms per particle.

But the second part is 4.2?

[Borek]

I don't know how many atoms per particle.

Look at the particle (or rather molecule, sometimes I am thinking in Polish and writing is English) formula.

But the second part is 4.2?

Yes (unless you are answering my question and you think 4.2 mole of HCl reacts with 1 mole of Mg ).

[Shea]

Do I multiply it by 2 because it's F2?

[Will]

Do I multiply it by 2 because it's F2?

Yup!