# What is the Mole? Molar Mass

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What is the Mole? Molar Mass
Unit 5 – The Mole What is the Mole? Molar Mass

We count pieces in MOLES.
How do we measure items? You can measure mass, or volume or you can count pieces. We measure mass in grams. We measure volume in liters. We count pieces in MOLES. 2

A. What is the Mole? A large amount!!!! VERY
A counting number (like a dozen) Avogadro’s number 1 mol = 6.02  1023 items A large amount!!!! VERY

Similar Words for an amount
Pair: 1 pair of shoelaces = 2 shoelaces Dozen: 1 dozen oranges = 12 oranges Gross: 1 gross of pencils = 144 pencils Ream: 1 ream of paper = 500 sheets of paper

Practice… If I have 1 mole of marshmallows, how many do I have?
If I have 2 moles of jelly beans, how many do I have? If I have 6.02 x 1023 pennies, how many do I have? 6.02 X 1023 Marshmallows 2 moles x 1023 jelly beans 1 mole = 1.2 x 1024 jelly beans 1 mole of pennies

A. What is the Mole? HOW LARGE IS THE MOLE??
1 mole of hockey pucks would equal the mass of the moon! 1 mole of basketballs would fill a bag the size of the earth! 1 mole of pennies would cover the Earth 1/4 mile deep!

Why do we need the mole? The mole is used as a mass comparison for any element in the periodic table. We can compare the mass in grams of any two elements only if they contain the same number of atoms. Remember 1 dozen Golf balls vs. 1 dozen marbles 8

Why 6.02 x 1023 ? Where did this number come from?
This is the number of atoms in exactly 12.0 grams of Carbon-12. This is the standard for the mole! It is a very large number, because atoms are so small!

Molar Mass – the mass in grams of one mole of atoms or molecules.
Atomic Mass = the mass of one atom of any element in atomic mass units (amu). Molar Mass – the mass in grams of one mole of atoms or molecules. 1 Sodium atom weighs – 23 amu’s 1 mole of Na atoms weighs – grams

Molar Mass Examples carbon sulfur Copper 12.01 g/mol 32.07 g/mol

Molar Mass Molar mass is the generic term for the mass of one mole of any substance (expressed in grams/mol) The same as: 1) Gram Molecular Mass (for molecules) ) Gram Formula Mass (ionic compounds) 3) Gram Atomic Mass (for elements) molar mass is just a much broader term than these other specific masses

Calculating Molar Mass for Compounds
Molar mass is determined by the adding the weights of all the atoms in a compound. Calculate the formula mass of magnesium carbonate, MgCO3. 24.3 g g x (16.00 g) = 84.3 g Thus, 84.3 grams is the formula mass for MgCO3.

Compound Molar Mass Examples
water sodium chloride H2O 2(1.01) = g/mol NaCl = g/mol

Molar Mass Examples sodium bicarbonate NaHCO3
sucrose NaHCO3 (16.00) = g/mol C12H22O11 12(12.01) + 22(1.01) + 11(16.00) = g/mol