THE MOLE
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Transcript of THE MOLE
THE MOLE... a unit of counting
Review
• How many oxygen atoms in the following?CaCO3
Al2(SO4)3
•How many ions in the following?
CaCl2NaOHAl2(SO4)3
3 atoms of oxygen x 6.022 x 10 23
12 atoms of oxygen x 6.022 x 10 23
3 total ions x 6.022 x 10 23
2 total ions x 6.022 x 10 23
5 total ions x 6.022 x 10 23
Finding Number of Atoms or Molecules
How many atoms of copper are there in 2.0 moles?
N = nNA
Given:
n Cu = 2.0 mol
NA = 6.02 X 1023
N = nNA
= 2.0 mol X 6.02 X 1023 atoms
1 mol
= 1.2 X1024 atoms of copper
• Do you know how to measure out 3 moles of sugar or salt or water?–The mole is a counting unit, so we would have to count out 6.02x1023 particles of each substance. (no thank you)
• There are 2 ways we can use to measure out a number of moles of a substance.–Measure it in grams (a mass)–Or measure it in liters (a volume)
How we measure moles…
Using a formula
• N = Number of particles , ions, atoms, molecules or formula units
• NA = Avogadros number• n = number of moles • n = N / NA • N = n x NA
• Note on calculator x 10 is the same as EXP or EE. DO NOT use them both
• On calculator use 6.022 EXP 23
NNA n
Mole Calculations
MM
m
n
MM = m/n
n = m/MM
m = MMn
Factor Label! Let the units guide you
N = nNA
n = N/NA
Determining Molar MassThe mass of one mole is called “molar mass”
E.g. 1 mol Li = 6.94 g Li This is expressed as 6.94 g/mol Symbol MM
What is the molar mass of CO2?
Recall: Add the individual molar masses MM(NH4)3PO4 = 3(N + 4H) + P + 4O
= 3N + 12H + P + 4O = 3(14.01) + 12(1.01) + 30.97 +
4(16.00) = 149.12 g/mol
The same as: Gram Molecular Mass (for
molecules) Gram Formula Mass (ionic compounds) Gram Atomic Mass (for elements)
molar mass is just a much broader term than these other specific masses
Converting Mass to Moles
Example: How many moles of calcium carbonate are there in 1.5 kg?
MM = m/n
n = m/M
m = Mn
Given:
m CaCO3 = 1500 g
MM = 40.08 + 12.01 + (3 X 16.00)
= 100.09 g/mol
n = m/MM
= 1500 g 100.09 g/mol
= 15 mol
n = 1500 g X 1 mol
100.09 g
= 15 mol
Converting Moles to Mass
Example: What is the mass in grams of 0.346 mol of sodium sulfate?
MM = m/n
n = m/M
m = Mn
Given:
n Na2SO4 = 0.346 mol
MM = (2 X 22.99) + 32.06 + (4 X 16.00)
= 142.04 g/mol
m = MMn
= 142.04 g X 0.346 mol
1 mol
= 49.1 g
Try These:
How much would 2.34 moles of carbon weigh?
How many moles of magnesium is 24.31 g of Mg?
28.1 grams C
1.000 mol Mg
How many sugar (sucrose, C12H22O11) molecules are there in a 1.00 kg bag?
Given:
m = 1.00 X 103 g
MM = (12 X 12.01) + (22 X 1.01) + (11 X 16.00)
= 342.34 g/mol
n = 1.00 X 103 g X 1 mol
342.34 g
= 2.921 mol
N = nNA
= 2.921 mol X 6.02 X 1023 molecules
1 mol
= 1.76 X1024 molecules of sugar
How many carbon atoms are there in a 1.00 kg bag of sugar (sucrose, C12H22O11) ?
N = 1.76 X 1024 molecules of sugar X 12 carbon atoms
1 molecule sugar
= 2.11 X 1025 carbon atoms
Moles
(mol)
Mass
(g)
# of molecules/atoms/ions
Volume (L) at STP
(0˚C, 101.3 kpa)
Concentration (mol/L)
6.02 X
1023
g/mol
22.4
Vol
Learning check
1.How many atoms of Cu are present in 35.4 g of Cu?
2.How many atoms of K are present in 78.4 g of K?
3.What is the mass of 1.20 x 1024 molecules of glucose (C6H12O6)?
= 3.35 X 1023 atoms Cu
= 1.21 X 1024 atoms K
= 359 g
Learning Check!
How many atoms of O are present in 78.1 g of oxygen?
78.1 g O2 1 mol O2 6.02 X 1023 molecules O2 2 atoms O 32.0 g O2 1 mol O2 1 molecule O2
Measuring volumeMOLAR VOLUME, Vm Volume occupied by 1 mole of any gas
22.4 L at STP (standard temperature and pressure) at 0°C and 1 atmosphere/ 103kPa (kilopascals)
24.8 L at SATPStandard Ambient Temperature and Pressure
( 20oC and 1 atmosphere )
Particles to moles or moles to particles
Mass to moles or moles to mass
Volume to moles and moles to volume
V = n x Vm
HOMEWORK• Finish Grams-Mole
Worksheet • Mole Worksheet –
Due Tuesday, April 9th