1. Lecture 51 Measuring Matter Ozgur Unal
NIS – CHEMISTRY
Lecture 51
Measuring Matter
Ozgur Unal

2. The Mole
The mole, abbreviated mol, is the SI base unit to measure the amount of a substance.
A mole is defined as a the number of carbon atoms in exactly 12 g of pure carbon-12.
A mole of anything contains x 1023 representative particles  Avogadro’s number.
A representative particle is any kind of particle: atom, molecule, formula unit, electron or ion.
Amadeo Avogadro, in 1811, determined the volume of 1 mole of gas.
This is why x 1023 is also called Avogadro’s number.

3. The Mole 1 mole of Na contains 6.0221367 x 1023 Na atoms.
1 mole of O2 contains x 1023 O2 molecules.
1 mole of CH4 contains x 1023 CH4 molecules.
1 mole of NaCl contains x 1023 NaCl formula unit.
1 mole of electron contains x 1023 electrons.
1 mole of Mg+2 contains x 1023 Mg+2 ions.
In the rest of the lectures,
we will use 6.02 x as
Avogadro’s number.

4. Converting Between Moles and Particles
1 dozen of rose = 12 roses
How many roses are there in 4.5 dozens of rose?
1 mole of representative particles = 6.02 x 1023 representative particles
Using this relationship you can convert moles ro representative particles, and reprsentative particles to moles.
Example: How many molecules are there in 3 moles of CO2?
3 moles of CO2 = 3 moles of CO2*6.02 x 1023 molecules/1 mole
3 moles of CO2 = x 1024 CO2 molecules
Example: How many atoms are there in 3.5 moles of Xe.
Example: How many moles are there in 3.01 x 1024 ions of Cl-.