1. UNIT 3 – Chemical Quantities
(5.2) The Mole

2. The Mole
The mole is a common measure of matter in a chemical reaction.
One mole (1 mol) of a substance contains 6.02 x 1023 particles of the substance. or
1 mole = 6.02 x 1023 elementary entities

3. The Mole- Examples
1 mole of carbon contains 6.02 x atoms of carbon
1 mole of H2O contains 6.02 x molecules of H2O
1 mole of NaCl contains 6.02 x formula units of NaCl

4. What’s this called?
This value of 6.02 x 1023 is called Avogadro’s Number (NA)
We use other common measures
- 1 dozen = 12
- 1 baker’s dozen = 13
- 1 gross = 144

5. Big Numbers ? Six hundred and two sextillion 602 x 1021
The largest number-word used by the early Romans was "mille", meaning thousand. A distance of one thousand paces was "milia"; we call this distance a "mile". The suffix "ione" implies an unusually large size. So when a number bigger than one thousand (mille) was needed, the word chosen was: "mille ione" ---> "million" = 1,000,000 or 106. The Latin prefix "bi" is the 2nd in the series of prefixes, another mille (1,000 times) so leads us to "billion", or 109. For bigger numbers, these Latin prefixes are used: tri, quad, quint, sext, sept, etc. – each another mille hence 1012, trillion; 1015, quadrillion; 1018, quintillion; 1021, sextillion; 1024, septillion What is the name of the number, 6.02 x 1023?
Six hundred and two sextillion 602 x 1021

6. Converting moles to number of particles
N = n NA
Where:
N = number of particles
n = number of moles (unit: mol)
NA = Avogadro’s constant (6.02 x 1023)

7. Sample Problems:
1. Find the number of atoms in 3.0 moles of gold. 2. Find the number of molecules of water in 0.64 mol of water. 3. How many atoms are present in 5.0 mol of carbon dioxide? 4. How many oxygen atoms are there in mol of H2SO4?

8. Converting number of particles to moles
n = N NA
Sample Problems 5. It is determined that a sample of ammonia contains 3.25x1022 molecules. How many moles of ammonia are present? 6. How many moles are present in a sample of NaCl that contains 3.58x1024 formula units of NaCl? 7. How many moles of K1+ ions are there in a sample of K3PO4(s) that contains 3.82x1024 formula units of K3PO4(s) ?

9. Homework
Read p
Do p #13-22
p 179 #1-8, 10