Mole Conversions
We will soon learn to love the mole as it is at the heart of chemistry.
All conversions go through the mole:
Examples: Convert to moles
48.8g Al (1 mole Al) = 1.80 mol Al
( 27.0g )
3.12g CO2 (s) (1 mole CO2) = .0710 moles CO2 = 7.10 x 10-2 moles
( 44.0g )
To convert between grams and moles, we need to first calculate the
molar mass of the material. We do this by adding the atomic (also
called molar) masses of the table.
Eg. NH4SO4
N= 1 x 14.0 = 14.0
H= 4 x 1.00 = 4.00
S= 1 x 32.1 = 32.1
O= 4 x 16.0 = 64.0
114.1g/mol
Q. What is the mass of 6.2 moles of ammonium sulphite?
R. 6.2 moles NH4SO4 (114.1g NH4SO4) = 7.1x102g NH4SO4
( 1 mol NH4 )
Q. What is the mass of 3.10x102 moles of NH3?
R. 3.10x102 moles NH3 (17.00g NH3) = 5.3 x 103g NH3
1 mol NH3
To convert between atoms and moles, we need avagadro’s number.
Ex: Given 2 moles of Ca atoms, how many atoms are present?
2.0 moles Ca (6.02x1023) = 1.2x1024 atoms Ca
1 mole
-1
Ex: Given 3.6x10 moles of AgCl, how many molecules?
.36 moles AgCl (6.02x1023 molecules) = 2.2x1023 molecules
1 mole
Ex: How many H atoms are found in 6.4 moles of CH4?
6.4 moles CH4 (6.02x1023 CH4) (4 atoms H) = 1.5x1023 H atoms
1 mole
1 CH4
We can go backwards from particles to moles:
Ex: Given 9.6x1015 molecules of C6H12O6, how many moles is this?
9.6x1015 C6H12O6 ( 1 mole ) = 1.6x10-8 moles
6.02x1023
Ex: I give Mr.P 15,000,000,000,000 atoms of gold. How much does
this weigh? (gold is $11.00/g)
1.5x1013 atoms Au ( 1 mole ) ( 197.0g Au ) = 4.9x10-9 g Au
6.02x1023 1 mole Au
= $.0000054
Ex: Mr.B is given 3.4g of Pt. He gets 1¢ per atom. How rich is he?
3.4g ( 1 mole ) (6.02x1023) ( $.01 ) = $1.0x1020
195.1g
1 mole
1 atom