2-5 Bellwork
1. How many moles are 2.3x1023
molecules of water?
2.3E23 ÷ 6.02E23 = 0.38mol
2. How many atoms are in 3mol H2O?
3mol x 6.02E23 = 1.8E24
1. How many moles of H are there in
2mol H2O?
2*2= 4 mol H
2. How many moles of O are there in
5.5 moles of SO4?
5.5*4= 22
1. If there are 2.2 moles of CO2, how
many atoms of Oxygen are there?
2.2* 2 * 6.02E23 = 2.6E24
2. If there are 5mol of Carbon Dioxide,
how many atoms of oxygen are there?
5 * 2 * 6.02E23= 6.02E24
Molar Mass
Does a dozen marbles have the same mass as a
dozen bagels?
Different elements, diff. Molar Mass
Molar Mass
• Carbon has a molar mass
of 12 grams/mole
• Molar mass of oxygen = 16
• Find the molar mass of H=1x2
O=16__
water
18g/mol
Molar Mass= how much 1 mole of a
substance weighs
NaCl
Na= 23 g/mol
+ Cl= 35.4 g/mol
58.4 g/mol
Determine the molar mass
•
•
•
•
•
•
•
Nitrogen trihydride NH3 =17g/mol
Copper (II) Sulfate 63.5+32+4(16)=160
Sodium Chloride 58.5
Silver (I) Chloride 143
Silver 107.9
Oxygen gas 32
Nitric Acid 63
• 1 donut=10g
• How much do 12 donuts weigh?
= 10g x 12 donuts= 120g
How many donuts are in 20g of donut?
=20/10= 2 donuts
Atoms,
molecules,
particles,
formula units
X molar mass
÷ molar mass
÷ 6.02E23
X 6.02E23
Moles
Mass
(grams)
How many moles in 400g of gold (Au)?
400÷197=
2mol
What’s the mass of 3mol NaCl?
3x58.5=
175.5g
• What’s the mass of 10mol of Fe?
10mol Fe x 56g Fe = 560g
• What’s the mass of 3.3mol of NaCl?
3.3mol NaCl x 58.5NaCl = 193g
• What’s the mass of 5mol of S?
5mol S x 32g/mol S =160g
• What’s the mass of 4.25mol of CO2?
4.25mol CO2 x 44g/mol = 187g
• How many moles are 32g of H2O?
32g ÷ 18g = 1.7mol H2O
• How many moles are 60g of Br?
60g ÷ 80g = 0.75mol Br
• How many moles are 150g of CaO?
150g ÷ 56g= 2.7mol CaO
1. How many moles are 100g of gold
(Au)?
100g ÷ 197g = 0.5mol H2O
2. How many grams are 4mol of NH3?
4mol x 17= 68g
• How many atoms of Cl in 10g of CaCl2 ?
End here!
Start here!
• How many atoms are in 10g of Ca ?
10g ÷ 40g x 6.02E23= 1.5x1024 atoms
• How many atoms in 46g of Na?
• How many molecules of H2O are in
75g of water?
• How many grams is 1.2x1024 atoms of
gold (Au)?
• What’s the mass of 3.1x1024 particles
of KCl?
What big things have we learned???
• The Mole is just a ____________
of something.
COUNT
• If you know the chemical formula of a substance you can
MOLAR MASS
know its ________
______
DIVIDE
MOLAR MASS
• When given mass ____________
by the ________
______
MOLETIPLY
• If you have MOLES__________________
MOLES
RATIO of __________
• A Chemical Formula is a __________
The Mole Lab
Water
50 mL
Salt
One Scoop
Copper (II) Sulfate
1 piece
Formula
Mass (grams)
Molar Mass
Moles of each
compound
H:
O:
Na:
Cl:
Cu:
S:
O:
Moles of each
element
H:
O:
Na:
Cl:
Cu:
S:
O:
Atoms of each
element
H:
O:
Na:
Cl:
Cu:
S:
O:
Brain Break…
• http://www.youtube.com/watch?v=TEl4jeET
Vmg
What is “STP?”
Standard
Temperature and
Pressure
0.00oC
1.00 atm
Avogadro’s Principle
• At STP, 1mol of any gas (6.02x1023
particles) occupies 22.4L volume
1mol
H2
22.4L
1mol
O2
22.4L
Mole Volume (x22.4)
• A chemical reaction produces 0.37 mol of N2 gas.
What volume will that gas occupy at STP?
0.37molN2 x
22.4L
1 molN2
= 8.2L
VolumeMole (÷22.4L)
• How many moles in 50L of gas at STP?
MoleVolumeMass
• A container has 0.884 mol of Neon gas at STP.
What volume will it have? What mass will it
have?
0.884mol Ne x 22.4L
1 molNe
0.884mol Ne x
20 g Ne
1 molNe
Practice Problems!
• P.453 #21, 23