1. THE MOLE CONCEPT

2. THE DOZEN ANALOGY Coin Mass of one coin Dozen Mass Number of Coins
Penny
2 g
24 g
12 pennies
Nickel
4 g
48 g
12 nickels
Dime
1.5 g
18 g
12 dimes
Quarter
7 g
84 g
12 quarters

3. THE MOLE CONCEPT Objects are measured by counting or by weight (mass)
It’s easier to measure large objects by counting
Elephants, cars, eggs
It’s easier to measure small objects by weight (mass)
Nails, rice, pellets

4. THE MOLE CONCEPT Chemist handle chemicals in two ways
Chemicals that we can see and measure in the lab
16 grams of CH4 or 32 grams of O2
Molecules that we in our heads that move and combine to form new products
CH4 + 2 O2 → CO2 + 2 H2O

5. THE MOLE CONCEPT
Through experiments we can find the relative mass of molecules
One molecule of CH4 has a mass of 16 a.m.u. (atomic mass units)
One molecule of O2 has a mass of 32 a.m.u.
Knowing the mass of just one molecule is not very helpful in the lab because one molecule is just too small.

6. THE MOLE “n” The mole term is similar to the “dozen” term.
Just as a dozen represents “12”; the mole represents x A very large amount.
This is due to atoms & molecules being very small.
THE MOLE “n”
The mole is also referred to as Avogadro’s number, NA
1 mole = NA= n = x 1023 particles
Particles could be atoms, molecules, ions, electrons, even eggs.

7. 1 mole of any substance = 6.02 x 1023 units of that substance.
IMAGINE:
1 mole of any substance = 6.02 x 1023 units of that substance.
If you spread 1 mole of un-popped popcorn kernels across the USA the entire country would be covered in popcorn to a depth of over 9 miles.
If 1 mole of marbles were spread over the surface of the Earth, our planet would be covered by a 50-mile thick layer of marbles.
1 mole of soft drink cans would cover the surface of the earth to a depth of over 200 miles

8. THE MOLE CONCEPT Substance Gram Molecular Mass (grams)
Number of Particles (Molecules)
CH4
16 g
6.02 x 1023 O2
32 g
CO2
44 g
H2O
18 g

9. Defining the Mole Definition of the mole (mol)
One mole is the amount of any substance that contains the same number of units as the number of atoms in exactly 12 grams of Carbon-12
1 mole of any substance = 6.02 x 1023 units of that substance. (unit = molecules, formula units, or atoms)
6.02 x 1023 is known as Avogadro’s Number

10. THE MOLE & ATOMIC MASS
The atomic mass (weight) is measured in reference to the mole.
The atomic mass is also known as the MOLAR MASS.
The atomic mass = mass of an element DIVIDED by 1 mole of that element.
Atomic mass = mass/mole or m/n.
Units for atomic mass is grams per mole or g/mol.
For example:
H = amu
= g/mol
= x 1023 atoms
= 1 molar mass

11. CALCULATIONS INVOLING THE MOLE.
Fill in the blank.
A mole of oxygen atoms contain _______ atoms and weighs ______ grams.
A mole of oxygen contains _____ molecules and ____ atoms and weighs _______ grams.
A mole of fluorine atoms contain _________ atoms and weighs _____grams.
A mole of fluorine contains __________ molecules and ________ atoms and weighs ______ grams.
6.022 x 1023
6.022 x 1023
15.999
19.00
6.022 x 1023
6.022 x 1023
2(6.022 x 1023 )
x 1023
or 2(15.999)
38.00

12. CALCULATIONS INVOLING THE MOLE.
How many atoms of Mg are contained in 15.0 grams of Mg?
Answer:
15.0 g (1 mole/24.3g) =
0.617 moles.
then
0.617 mol (6.022 x 1023 atoms/ 1 mole) = 3.72 x 1023 atoms.
Dimensional Analysis Approach.
How many moles of Mg are contained in 15.0 grams of Mg?
Answer:
15.0 g (1 mole/24.3g) =
0.617 moles.
Remember if “g” is on top originally then inside the parenthesis it must go on the bottom.

13. MOLAR MASS FOR COMPOUNDS
The molar mass of any substance is the mass in grams for one mole of that substance.
H2SO4 contains 2-H atoms, 1-S atoms & 4-O atoms. Each of those atoms contribute mass to the whole compound.
2H + 1S + 4O = H2SO4 so
2(1.008 g/mol) + 1(32.06 g/mol) + 4(15.99 g/mol)
= g/mol
Calculate the molar mass of the following compounds.
1. K3PO4
2. Ca(OH)2
3. (NH4)2SO3
4. SrCl2 . 6H2O
answer on next page.

14. MOLAR MASS FOR COMPOUNDS
Answer to molar mass question.
1. 3K + P + 4O =
212 g/mol
2. Ca + 2O + 2H =
74 g/mol
3. 2N + 8H + S + 3O =
116 g/mol
4. Sr + 2Cl + 12H + 6O =
267 g/mol
Word Problems:
How many grams does one molar mass of BaCO3 weigh?
Answer: : 197 g/mol

15. CALCULATIONS INVOLING THE MOLE for COMPOUNDS.
How many atoms are in 6.34 g of (NH4)3PO4
Answer:
3N + 12H + P + 4O = 149 /mol
then
6.34 g (1 mole/149 g) =
moles.
mol (6.022 x 1023 formula units/ 1 mole) (20 atoms/1 formula unit) = 5.12 x 1023 atoms.
Dimensional Analysis Approach.
How many grams of NH4NO3 are contained in 3.15 moles of NH4NO3?
Answer:
2N + 4H + 3O = 80 g/mol
3.15 mol (80 g/mol) =
252 g
Remember if “mol” is on top originally then inside the parenthesis it must go on the bottom.

16. Challenge MOLE problems.
What mass of sodium will contain the same number of atoms as g of potassium?
100.0g K (1 mole K / 39.1 g K) (6.022x1023 K-atoms/1 mole K) = x K-atoms.
Now since atoms of K = atoms of Na
1.540x1024 atoms Na (1 mol/ 6.02 x1023 atoms) (22.98 g/ 1 mol) = g of Na

17. Challenge MOLE problems.
A solution of sulfuric acid contained 65% H2SO4 by mass and had a density of 1.56 g/mL. How many moles of acid are present in 1.00 L of the solution?
1.00L (1000 mL/1L) = 1000 mL of solution
dV = m mL (1.56 g/mL) =1560 g of solution
but only 65% of the solution is H2SO4 therefore:
65 % = (x / 1560 g) 100 so x= mass of H2SO4 = 1014 g
1014 g H2SO4 (1 mole / g) = 10.3 moles

18. PRACTICE PROBLEM #10 1. What is the molar mass of Fe(NO2)3.6H2O
2. How many moles are contained in g of Fe(NO2)3?
3. How many grams of iron are contained in mol of Fe2(CO3)3?
4. How many atoms are contained in 25.0 g of nitrogen (N2)?
5. How many grams of potassium nitrite will contain 6.78 x potassium atoms?
6. If 25.0 g of calcium chloride reacted with 25.0 g of sodium carbonate, how many moles of each will be reacting?
301.9 g/mol
3.868 mol
11 g
1.07 x 1024 N-atoms
957 g
CaCl2 = mol & Na2CO3 = mol

19. GROUP STUDY PROBLEM #10
______1. What is the molar mass of Ba(NO3)2.4H2O
a) b) c) d) 1044
______2. How many moles are contained in 54.78g of Cu(NO3)2?
a) mol b) mol c) mol d)
______3. Which contains the larger number of molecules?
a) g HCl b) g C6H12O6 c) g of I2
______4. How many grams of silver are contained in mol of AgNO3?
a) g b) g c) 128g d) 170g
______ g of nitrogen (N2) contains
a) atoms of N c) x 1023 atoms of N
b) mole of N d) atomic masses of N
______6. How many atoms are in 56.9 g of potassium nitrite?
______7. If g of calcium chloride reacted with g of sodium carbonate, how many moles of each will be reacting?

20. WE DIG CHEMISTRY