Transcript Unit: Chemical Quantities

Unit: Chemical Quantities
Measuring Mass with the Mole
After today, you will be able to…
• Calculate molar mass of a
substance
• Use molar mass to calculate the
mass of a substance given then
number of moles and vice versa
Atomic Mass vs. Molar Mass
The atomic mass on the
Periodic Table is the mass of a
single atom in amu (atomic
mass units).
Example: 1 carbon atom=
12.01 amu
Atomic Mass vs. Molar Mass
The molar mass (MM) = mass
of one mole of a substance. It
is equal to the atomic mass in
grams.
Example: 1 mole of carbon
atoms = 12.01 grams
Molar Mass Examples
Example: What is the molar mass
of Al2S3?
2Al = 2(26.98) = 53.96 Round molar masses two
decimal places to the right!
3S = 3(32.07) = +96.21
150.17g Al2S3=1 mol Al2S3
Molar Mass Examples
Example: What is the molar mass
of Ba3(PO4)2?
3Ba = 3(137.33) = 411.99
61.94
2P = 2(30.97) =
8O = 8(16.00) = +128.00
601.93g Ba3(PO4)2=1 mol Ba3(PO4)2
Example: What is the mass of 1.33
moles of Ba3(PO4)2?
K: 1.33 mol Ba3(PO4)2
U: ? g Ba3(PO4)2
1.33 mol Ba3(PO4)2
1
x
601.93g Ba3(PO4)2 . =
1 mol Ba3(PO4)2
801g Ba3(PO4)2
Example: How many moles are
equal to 157.8g of CaCl2?
K: 157.8 g CaCl2
U: ? mol CaCl2
157.8 g CaCl2
1
1Ca = 1(40.08) = 40.08
2 Cl = 2(35.45) = +70.90
110.98
x 1 mol CaCl2 . =
110.98 g CaCl2
1.422 mol CaCl2
Time to Practice!
Complete WS 2