# The Mole Chapter 10.

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The Mole Chapter 10

Formula Mass: Is what a single molecule “weighs” in amu’s (atomic mass units) Revision: So, 1 molecule of Water (H2O) weighs: 2 x 1.01 (for H) + 1 x (for O) = amu’s

Example #2: What is the mass of 1 molecule of Sugar(Sucrose)? (C6H12O6) C: 6 x = H: 12 x = O: 6 x = Do other examples? a) CO2 b) (NH4)2CO3

1 dozen = 1 baker’s dozen = 1 score = 1 gross = The Mole:
First, let’s look at names that reflect numbers: 1 dozen = 1 baker’s dozen = 1 score = 1 gross =

Let’s now focus on a particular isotope – Carbon-12
1 Carbon-12 atom weighs ______________ But this is an impractical measurement. We want to work in the mass unit of grams. So, how many atoms of Carbon-12 would it take to weigh g.?

Amadeo Avogadro (Italian, ) calculated the number to be x 1023 and is also known as a So now, the average atomic mass number also represents how many grams that element would weigh if you had 1 mole of that substance.

So, 1 mole of Water weighs:
H: 2 x g/mole = g/mole O: 1 x g/mole = g/mole This # is known as the _____________(mass of 1 mole) of Water. Examples. Calculate the Molar Mass of the following: a.) SO2 b.) (NH4)3PO4

Mole to Mass & Mass to Mole Conversions
If we are given the # moles of a substance and we want to calculate how much it weighs (i.e. what’s its mass?), then we convert by using the _________________________! E.g. What is the mass of 1.50 moles of Water? 1.50 mol. Of H2O x g of H2O = g of H2O mol. of H2O E.g.#2 What is the mass of 0.75 mol. Of Salt?

Now, going the other way. How many moles are in 100.g of CO2 ? 100.g of CO2 x 1 mol. of CO2 = _______________ g of CO2 E.g.#2 How many moles are in a pound of Sugar?

Converting from moles to molecules & vicy versi
In these conversions, instead of using the _________________________, you use Avacado’s Avagadro’s Number. (NA) Ex. How many molecules are in 1.50 moles of Water? (remember: 1 mole = 6.02 x 1023 ) 1.50 mol. x x 1023 molecules = ___________________ mol. Ex.2) How many moles in x 1024 molecules of Salt? 2.107 x 1024 molecules x ____ = 3.50 moles x 1023 molecules

Do these in-class egg samples:
1.) How many molecules are in 0.02 moles of Sugar? 2.) How many moles are in 3.01 x 1023 molecules of O2? Let’s look at lots of molecules of Water.

Time to draw a MOLE diagram
I know what you’re thinking! Now we can do Mass to Molecules conversions & vicy versi. (Hint: it’s a 2 step Chain Method) Ex. How many molecules are in 12.0g (~½ oz) of Water? 12.0g of H2O x _____________x________________________ mol of H2O = 4.00 x 1023 molecules of H2O Ex. What does 9.03 x 1022 molecules of Vitamin C weigh? (Vitamin C = C6H8O6)

Standard Molar Volume The Volume occupied by 1 mole of a gas is the Molar Volume. The Volume occupied by 1 mole of a STP is known as the Standard Molar Volume of a gas and is equal to 22.4 L. STP V = 22.4 L/mol.  V = n x 22.4 L/mol. n So 1 mole of any gas occupies STP, but their masses may be different.

So 2 moles of a gas will occupy twice the space (Volume) of 1 mole.
e.g. 2H O  H2O (more examples: N2 + H2  NH3 ,…) And remember:1 mole = 6.02 x 1023 molecules

(Diagram – New Mole Diagram)

Add that to the mole diagram…
Mass (Grams) Mole Molecules/ Atoms