Atomic Molar Mass - Prairie Spirit Blogs

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What is a mole?
Stoichiometry
The Mole
Chemists use a measurement called ‘the mole’
A mole is like a dozen eggs= 12 eggs or a pair of shoes= 2 shoes
However, the mole is a very large number
This is because atoms are so small that chemists need a lot to be able to find their mass
How big is the mole??
A mole contains 6.023 x 1023 of anything
6.023 x 1023 is a.k.a AVOGADRO’S NUMBER
How big is a mole exactly?
 If you could count 10 million numbers every second, it would take you 2 billion years to count
an avogadro’s number out
 If you had a mole of unpopped popcorn kernals it would cover the entire planet to a depth of
9 miles
 If you poured out a mole number of cans of pop out you would cover the entire earth with an
ocean of pop 200 miles deep
Therefore,
1 mole= 6.023 x 1023 particles or
6.023 x 1023 particles/mol
 1 mole Cl= 6.023 x 1023 particles
 1 mole of H= 6.023 x 1023 particles

2 moles=
Atomic Molar Mass
The mass (in grams) of 1 mole of a given element
To find this for each element you must look at the periodic table:
1 mole of C= 12 g (or 12g/mol)
What is the mass of 1 mole of oxygen?
What about 2 moles of oxygen?
3 moles?
Molecular Molar Mass
Is the mass (in grams) of all the elements in the molecule
To find the mass: 1. find each element’s atomic mass and 2. add all of the atomic masses together
Ex NaOH:
Na= 1 x 23 g/mol
O= 1x 16 g/mol
H= 1 x 1g/mol
40 g/mol of NaOH
Ex H2O
Ex. H2SO4
Find the following masses
MgBr2, Ga(NO2)3, CrI2, BeSO4
Assignment: molar mass worksheet
Stoichiometery
Given two out of these three values for mass, moles and/or molar mass, you can figure out the value of
the missing value
Mass= moles x molar mass
Moles= mass/molar mass
Molar mass- find using periodic table
Particles= moles x 6.023 x 1023
Examples
Moles to mass
2.0 mol of CaO
0.6 mol of BeSe
1.35 mol of Li3P
0.35 mol of Be2SO4
Find moles given mass
18.02 g of H2O
80.92 g of HBr
5.0 g of CaCl2
0.26g of Ca3(PO4)2
15.0 g of MgCl2
86.7g of H3PO4
examples
1 mol, 1mol, 0.045 mol, 0.00084 mol,0.16 mol, 0.885 mol
Assignments
Assignment: molar mass/ moles/mass assignment
examples
Moles to particles:
1 mol of Fe
3 mols CO
0.671 mols H2O
0.1001 HBr
6.023 x 1023, 18.069 x1024, 4.04x 1023, 6.023x 1022
Particles to moles
6.023 x 1023 atoms of Fe
1.20 x 1023 atoms of O2
2.4 x 1024 atoms of H
Examples
1.8 x 1024 atoms of K
mol, 0.199 mol, 3.987 mol, 2.99 mol
Examples
Mass from particles
mass of 1.20 x 1024 molecules of water?
mass of 2.41 x 1024 atoms of barium hydroxide?
mass of 1.51 x 1022 atoms of neon?
mass of 7.53 x 1022 molecules of CH4?
Particles from mass
How many molecules does 36.0 grams of water represent?
How many molecules does 11.0 grams of CO2 represent?
How many atoms does 3.0 grams of carbon represent?
How many formula units does 200.0 grams of calcium carbonate represent?
assignment
Stoichiometery problems with # of molecules
Stoichiometery assignment with all the examples
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