Avogadros Constant - 6.02 x 10^23 == Number of molecules in a single mole

24 dm^3 in 1 mole of gas

cm^3 → dm^3 = Divide by 1000

dm^3 → cm^3 = Multiply by 1000

Eg Question -

1. How many molecules are there in 2 moles of O2
   1. 2 x Avogadros
2. How many atoms are there in 2 moles of O2
   1. 2 x 2 x Avogadros
3. How many atoms are there in 50 grams of C
   1. Mol = 50/12 = 4.16
   2. 4.16 x Avogadros
4. How many molecules in 48 dm^3 of O2
   1. 1 mol = 24 dm^3, hence this is 2 moles
   2. 2 x Avogadros

Empirical Formula -

1. If percent or mass is given of the different substances simply divide the percentage of element X by the atomic mass of element X
2. Then after you find your values, divided all of those values with the smallest value gained by doing the above method
3. Make it so that the numbers are all whole numbers [no decimals]
4. Add the numbers obtained for each element as their subscript in the formula

Example -