Transcript Chapter 7 Notes, Part I

Chapter 11 Notes, Part I
What is a mole?
One Step Problems
What is a mole?
• A furry, burrowing woodland creature, revered
by many and adored by all?
Maybe!
• But not really in chemistry!
A Mole...
• is a unit of measurement that tells
how many particles of something
you have!
• much like a dozen (12), a gross (144) or a
ream (500) is just a unit that groups smaller
numbers into big ones...but its a big one; a
REALLY big one!
1 mole = 6.02 x 1023 particles!
(that’s a lot of flowers!)
What are particles?
• Particles could be anything, but because of the
size of the number, we usually mean
Atoms,
molecules, or
formula units.
Avogadro’s Number
• The number 6.02 x 1023 is called
Avogadro’s number.
• This is due to Amadeo Avagadro’s
research leading to the discovery, not the
discovery of the number itself.
It is a little known fact that Avogadro was voted
his class’s most likely to have a scientific
discovery and most likely to look really creepy.
Obj. 1…Formula vs. Molecular
Mass
• Formula mass = total mass of ionic compounds
- starts with a metal
• Molecular mass = total mass of molecular compounds
- starts with a non-metal
• To calculate…
- find mass of each element on P.T. (whole #s)
- multiply mass by subscript and/or coefficient
- add all masses together for total mass
Obj. 1 cont…
• Practice…
S3F6
32 x 3 = 96
19 x 6 = 114
Al2(SO4)3
27 x 2 = 54
16 x 12 = 192
32 x 3 = 96
96 + 114 = 210 amu
molecular mass
54 + 96 + 192 = 342 amu
formula mass
Obj. 1 cont…
two compounds chemically bonded together…
NOT multiply!!!
• more practice…
CuSO4  5H2O
3CaC2O4
40 x 3 = 120
OR
40 x 1 = 40
12 x 6 = 72
12 x 2 = 24
64
32
16 x 12 = 192
16 x 4 = 64
64
10
80
64 + 32 + 64 + 10 + 80 = 250 amu
120 + 72 + 192 = 384 amu
40 + 24 + 64 = 128 x 3 = 384 amu
Obj. 2 cont…
• recall that one p+ / n0 = 1.67 x 10-24 grams
• therefore…one mole of nucleons = 1 gram
** 1.67E -24 x 6.02E23 = 1
• amu = g/mole
atomic mass
molar mass
• one mole =
~ 6.02 x 1023 atoms, molecules or ions in a compound
~ molar mass of compound / element
~ 22.4 liters of any gas at STP (standard temp. and pressure)
0°C
273K
760 mmHg
101.3 kPa
1 atm
Obj. 3-7…Mole Conversions
• use ‘mole map’ to solve mole conversions…
** going away from moles = x
** going toward moles = ÷
 by molar mass
X by 22.4
Liters
 by 22.4
Mole
Grams
X by molar mass
X by 6.02 x 1023
 by 6.02 x 1023
# of atoms/
molecules
Obj. 3-7 cont…
• Practice, practice, practice…
1.2 x 1024 atoms He
2.0 moles He = ____________
2.0 moles x 6.02E23 =
2 16 = 18
36
2.0 moles H2O = ____________
grams H2O
2.0 moles x 18 =
3.00
67.2 liters O2 = ____________
moles O2
67.2 liters ÷ 22.4 =
2 16 = 18
1.5
27 grams H2O = ____________
moles H2O
27 grams ÷ 18 =
Obj. 3-7 cont…
• more practice…
6.00
3.61 x 1024 molecules NaCl = ____________
moles NaCl
3.61 x 1024 molecules ÷ 6.02 x 1023 =
110
5.0 moles CO2 = ____________
liters CO2
5.0 moles x 22.4 =
12
32 = 44
264
** 3.61 x 1024 molecules CO2 = ____________
grams CO2 **
3.61 x 1024 molecules ÷ 6.02 x 1023 = 6 moles x 44 grams =
Practice Problem #1
• How many moles are in 2.57 x 1025
atoms He?
Practice Problem #2
• How many molecules of CO2 are in
25.3 moles?
Practice Problem #3
• How many moles of O2 are in 29.3L
of O2 gas?
Practice Problem #4
• If you have 3.6 moles of N2O
(Nitrous oxide) how many liters
would you have?
Practice Problem #5
• How many grams of iron are in 3.5
moles?
Practice Problem #6
• How many moles of Na2O are in
355.1g?