1. CELEBRITY CHEMIST of THE DAY

2. Number of particles in one mole = Avogadro’s number = 6.02 X 10 23
MOLE CONCEPT
Unit of measure for matter
Number of particles in one mole = Avogadro’s number = 6.02 X 10 23

3. One mole of any substance contains 6.02 X 10 23 particles, therefore:
How many molecules are present in 4 moles of H2O? How many atoms are present?
SOLUTION:
One mole of any substance contains 6.02 X particles, therefore:
(4 moles) 6.02 X = X molecules
mole
Since there are 3 atoms per H2O molecule,
the total number of atoms is:
(3 atoms) 2.41 X molecules = 7.23 X atoms
molecule

4. MOLAR MASS
Mass of one mole = mass of one atom/molecule expressed in grams rather than atomic mass unit (amu)
1 amu = based on 1/12 the mass of C-12 (most common carbon isotope)
Example:
1 atom of He = 4 amus
1 mole of He = 4 grams
1 molecule of O2 = 2 x 16 amus/O = 32 amus
1 mole of O2 = 32 grams

5. FORMULA
NUMBER OF MOLES
GIVEN WEIGHT
MOLAR MASS = GW MM n =

6. How many moles of carbon atoms are contained in 4 g of carbon?
The atomic mass of carbon is 12 amu, therefore the molar mass of carbon is 12 grams.
4 g X 1 mole = mole C
12 g
CONVERSION
FACTOR
(from periodic table)

7. 2. How many moles of water are there in 36 g of water?
SOLUTION:
The molecular mass of H2O is 18 amu.
The molar mass of H2O is 18 g.
36 g X 1 mole = 2 moles H2O
18 g

8. 3. Calculate the mass of aluminum carbonate (Al2(CO3)3) in 5
3. Calculate the mass of aluminum carbonate (Al2(CO3)3) in 5.85 moles of the compound.
In Al2(CO3)3 , there are 2 Al, 3 C and 9 O
Formula mass = (2 X 27 g/Al) +
(3 X 12 g/C) + (9 X 16 g/O) = 234 g
Molar mass = 234 g
Mass of Al2(CO3)3 = 5.85 moles X 234 g = 1369 g

9. MOLAR VOLUME
Volume of one mole of solid and liquids = varies from one substance to another based on their density
Example:
1 mole of H2O (density = g/mL) has a mass of 18 grams and will therefore occupy 18 mL
1 mole of NaCl (density = g/mL) has a mass 58 g
(Na = 23 g + Cl = 35 g) and would occupy a volume of 26.8 mL (58 g /2.165 g/mL)
Volume of one mole of gas =equal to 22.4 liters at standard temperature (0oC) and pressure (1 atm or 760 mm Hg) (STP)
1 mole of O2 gas = 22.4 L at STP
1 mole of He = 22.4 L at STP

10. Since there are 22.4 liters of any gas at STP, the solution is
How many moles of nitrogen are present in 4.48 liters of nitrogen at STP?
Since there are 22.4 liters of any gas at STP, the solution is
4.48 L X 1 mole = 0.2 moles N2
22.4 L
CONVERSION
FACTOR

11. PERCENT COMPOSITION
Percent by mass of each element present in the compound.
% by mass of each element
Total mass of element X 100%
Total mass of compound =

12. What is the percentage composition of H2O?
% H in H2O
2 X 1 g x 100% =
18 g =
11.11 %
% O in H2O
1 X 16 g x 100% =
18 g
88.89% =
TO CHECK = %