Mole Lecture
A. Definitions:
grams that is
1. Molar Mass (Gram atomic weight): the mass in ______
numerically equal to the mass in amu
_____.
12.01 amu
a. mass of 1 carbon atom _________
12.01 g
b. mass of 1 mole of C _______
Avogadro’s # of anything.
2. Mole = ____________
3. Avogadro’s number = ___________
6.022 x 1023
1 mole (6.02 x 1023 atoms
4. Molar Mass = The mass in grams of ________
or molecules).
1 mole C = 12.011 g
5. What is the relationship between atomic mass units and grams?
1g
x
0.0005486 amu
9.11 x 10 -28 g
= 6.022 x 10 23 amu
B. Calculations based on the mole.
# atoms
6.022 x 1023
Mol
Must go through the mole
Molar
Mass
Mass (g)
Periodic Table
1. What is the mass of a Titanium atom in amu? Grams?
1 atom Ti = 47.88 amu
1 mol Ti
1 atom Ti x
6.022 x 1023 atoms
47.88 g
x
1 mol Ti
= 7.95 x 10 -23 g
(If no initial value is provided, round answer to 3 sig figs)
2. What is the mass of one mole of Titanium?
1 mol Ti = 47.88 g
3. How many (a) moles and (b) atoms of sulfur are there in 255 g of
Sulfur?
255 g x
7.95 mol S
1 mol S
32.07 g
= 7.95 mol S
6.022 x 1023 atoms S
x
1 mol S
= 4.79 x 1024 atoms S
4. How many (a) moles and (b) grams of Uranium are there in a
billion U atoms?
1 x 109 atoms U
x
1.66 x 10-15 mol U
1 mol U
6.022 x 1023 atoms U
x
238.03 g
1 mol U
= 1.66 x 10-15 mol U
= 3.95 x 10 –13 g U
(If no initial value is provided, round answer to 3 sig figs)
5. How many Cu atoms are there in a solid copper penny that has a
mass of 3.06 grams?
6.022 x 1023 atoms Cu
1 mol Cu
3.06 g x
x
1 mol Cu
63.55 g
= 2.90 x 1022 atoms Cu
6. What is the mass of one atom of silicon in (a) amu (b) grams (c)
pounds?
(a) 1 atom = 28.09 amu Si
1 mol Si
x
(b) 1 atom Si
6.022 x 1023 atoms Si
10-25
x
28.09 g
1 mol Si
= 4.67 x 10-23 g Si
(c) 1.03 x
lb. Si
7. What is the mass of 1500 sulfur atoms in grams?
32.07 g
1 mol S
1500 atoms S x
x
6.022 x 1023 atoms S
1 mol S
= 8.0 x 10-20 g S
IV. Molecular Mass (weight)
sum of the atomic masses in (amu) of
A. The molecular mass is the _____
all the atoms
______ in a molecule. The molar mass is the same mass
grams
but in ______.
1. What is the molecular mass of benzene, C6H6? What is the molar
mass?
78.12 g = 1 mole
6(12.01) + 6(1.01)
= 78.12 amu
or
78.12 g/mole
6C
6H
B. Substances that do not form molecules such as ionic solids do not
have a molecular weight; they have formula weights.
1. What is the formula mass of aluminum sulfite? Al2(SO3)3 the
molar mass?
distributive
2 (Al) + 3 (S) + 9 (O)
2 (26.98) + 3 (32.06) + 9 (16.00)
= 294.14 amu
= 294.14 g/mole
2. Calculate the molecular mass of TNT, C7H5N3O6.
7 (C) + 5 (H) + 3 (N) + 6 (O)
7 (12.01) + 5 (1.01) + 3 (14.01) + 6 (16.00)
= 227.14 amu
3. What is the formula mass (amu) of Cr(OH)2  18 H2O?
(Cr) + 38 (H) + 20 (O)
(52.00) + 38 (1.01) + 20 (16.00)
= 410.38 amu
VI. MOLES II:Moles & Formula
A. General Information:
6.022 x 1023 number of anything.
1. 1 mole = ____________
6.022 x 1023
Avogadro’s number = ___________.
6.022 x 1023atoms.
2. 1 mole of atoms = ___________
x 1023 molecules.
1 mole of molecules =6.022
__________
3. The atomic weight of oxygen is _____
16.00 amu.
a. One oxygen atom has a mass of _____
16.00amu.
b. One mole of oxygen atoms (6.02 x 1023 atoms) has a mass of
16.00 g This is called the _____
gram atomic weight.
_______.
4. The molecular weight (mass) expressed inamu
____ represents the
single molecule, while the molecular weight
mass of a ______
grams represents the mass of 1
mol of
expressed in ______
_____
molecules; this is called the gram molecular weight.
5. Substance that do not form molecules, such as ionic solids, do
not have a molecular weight. They have a formula weight that
when given in grams is called the gram formula weight and
1 mol or the compound. This is used in
represents the mass of _____
ionic substances.
6. Road Map:
Atoms
Molecules
Formula Units
Particles
6.022 x 1023
Molar Mass
Mol
Mass (g)
B. Sample Problems
Iron (III)/Ferric carbonate
1. 0.500 moles of Fe2(CO3)3 (________________________)
contains
how many moles of
a. Fe 0.500 mol x 2 mol Fe
= 1.00 mol
1 mol Fe2(CO3)3
b. C 3 x 0.500 c. O
9 x 0.500
1.50 mol
4.50 mol
2. Calculate the mass of one water molecule in
(a) amu
2 (1.01) + 1 (16.00) = 18.02 amu
(b) grams
1 molecule x
1 mol
6.022 x 1023 molec
x
18.02 g
1 mol
= 2.99 x 10-23 g
3.
(a) How much does 4.50 moles of water weigh in grams?
4.50 mol H2O
x
18.02 g H2O
1 mol H2O
= 81.1 g H2O
(b) How many molecules is this?
4.50 mol H2O
x
6.022 x 1023 molec H2O
1 mol H2O
= 2.71 x 1024 molec. H2O