1. Using the Avagadro constant in calculations.
h. demonstrate an understanding of, and be able to perform, calculations using the Avogadro constant
Connector
Define
Relative atomic mass
Molar mass
Empirical formula

2. Relative atomic mass
Molar mass
Empirical Formula
The mass of a single atom on a scale on which the mass of an atom of carbon—12 has a mass of 12 atomic mass units.
Is the formula mass in g
A formula that gives the simplest whole-number ratio of atoms in a compound.

3. The Mole
1 mole contains the same number of particles as there are atoms in 12g of carbon-12 atoms.
This number is called Avogadro's number or Avogadro's constant (NA) and is equal to x 1023 particles.
mole
Avogadro

4. Calculations using Avagadro’s number
1 mole of atoms or molecules contains x 1023 atoms or molecules
How many atoms are their in a 1 mole of helium?
Formula of helium = He
So 1 mole contains x 1023 helium atoms.
How many atoms are there in 1 mole of oxygen?
Formula of oxygen = O2
So number of atoms = 2 x x 1023 = x 1024
How many molecules are there in 1 mole of oxygen?
 Formula of oxygen = O2  
1 mole of oxygen contains x 1023 oxygen molecules

5. Calculations using Avagadro’s number .2
1 mole of atoms or molecules contains x 1023 atoms or molecules
If we have x 1023 neon atoms, how many moles of neon atoms are there?
Moles of neon atoms = ( x 1023) = 0.7 mol
(6.022 x 1023)
If we have x 1021 chlorine molecules (Cl2), how many moles of chlorine molecules are there? Moles of chlorine molecules = (6.022 x 1021) = mol (6.022 x 1023)

6. Calculations using Avagadro’s number .3
1 mole of atoms or molecules contains x 1023 atoms or molecules
How many hydrogen atoms and chlorine atoms are present in 1 mole of hydrogen chloride gas?     Formula = HCl
so 1 mole of HCl contains x 1023 hydrogen atoms and x 1023 chlorine atoms
How many oxygen atoms are there in 5 moles of oxygen molecules?
Formula = O2
So 5 moles of O2 contains 5 x 2 = 10 moles of oxygen atoms and 5 moles of oxygen molecules contains 10 x x 1023 = x 1024 oxygen atoms.
How many nitrogen and hydrogen atoms in 1 mole of ammonia molecules?

7. will contain 1 mole of nitrogen atoms (N)
Formula of ammonia = NH3
will contain 1 mole of nitrogen atoms (N)
and 3 moles of hydrogen atoms (H)    
1 mole of ammonia molecules contains x 1023 nitrogen atoms
and 3 x x 1023 = x 1024 hydrogen atoms
Note: 1 mole of molecules does not necessarily contain 1 mole of atoms of each element in the formula