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

The mass of a single atom on a scale on which the mass of an atom of carbon12 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.

Relative atomic mass

Molar mass

Empirical Formula

The Mole1 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 6.022 x 1023 particles. Avogadromole

1 mole of atoms or molecules contains 6.022 x 1023 atoms or molecules How many atoms are their in a 1 mole of helium? Formula of helium = He So 1 mole contains 6.022 x 1023 helium atoms.

How many atoms are there in 1 mole of oxygen? Formula of oxygen = O2So number of atoms = 2 x 6.022 x 1023 = 1.2044 x 1024

How many molecules are there in 1 mole of oxygen? Formula of oxygen = O2 1 mole of oxygen contains 6.022 x 1023 oxygen molecules

Calculations using Avagadros number

Calculations using Avagadros number .2If we have 4.2154 x 1023 neon atoms, how many moles of neon atoms are there?Moles of neon atoms = (4.2154 x 1023) = 0.7 mol (6.022 x 1023)

If we have 6.022 x 1021 chlorine molecules (Cl2), how many moles of chlorine molecules are there? Moles of chlorine molecules = (6.022 x 1021) = 0.01 mol (6.022 x 1023)

1 mole of atoms or molecules contains 6.022 x 1023 atoms or molecules

Calculations using Avagadros number .3How many hydrogen atoms and chlorine atoms are present in 1 mole of hydrogen chloride gas? Formula = HCl so 1 mole of HCl contains 6.022 x 1023 hydrogen atoms and 6.022 x 1023 chlorine atomsHow 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 6.022 x 1023 = 6.022 x 1024 oxygen atoms. How many nitrogen and hydrogen atoms in 1 mole of ammonia molecules? 1 mole of atoms or molecules contains 6.022 x 1023 atoms or molecules

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 6.022 x 1023 nitrogen atoms and 3 x 6.022 x 1023 = 1.8066 x 1024 hydrogen atoms

Note: 1 mole of molecules does not necessarily contain 1 mole of atoms of each element in the formula