Chapter 11 Mathematics & Chemical Formulas Unit 6 – The Mole.
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Transcript of Chapter 11 Mathematics & Chemical Formulas Unit 6 – The Mole.
![Page 1: Chapter 11 Mathematics & Chemical Formulas Unit 6 – The Mole.](https://reader035.fdocuments.net/reader035/viewer/2022062321/56649eab5503460f94bb0df1/html5/thumbnails/1.jpg)
Chapter 11 Mathematics & Chemical Formulas
Unit 6 – The Mole
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Atoms are too small/light
Atoms are too small and too light to count or mass as individuals– One Carbon-12 atom = 1.99 x 10-23 grams
We use this as the basis for atomic mass units. 1 Carbon atom is 12 amu.
– 6 protons + 6 neutrons = 12 “things” that make up the mass of a carbon atom
One amu = 1/12 of a carbon atom
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Atomic Mass & Formula Mass
Atomic mass - the mass of 1 mole of atoms (also known as “molar mass”)
Formula mass - the masses of all the atoms in an ionic compound. Ex: CaCl2
Molecular Mass – the masses of all of the atoms in a molecular compound. Ex: CH4
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Formula Weight (FW)
So, the formula weight of calcium chloride, CaCl2, would be
Ca: 1(40.1 amu)
+ Cl: 2(35.5 amu)
111.1 amu
To convert to molar mass, change amus to g/mol. 1 amu = 1 g/mol
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Molecular Weight (MW)
For the molecule methane, CH4, the molecular weight would be
C: 1(12.0 amu)
16.0 amu+ H: 4(1.0 amu)
The molar mass of methane would be 16.0 g/mol
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1 mole - different physical states
Moles provide a bridge from the molecular scale to the real-world scale.
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Examples of Molar Mass
List the molar masses of the following:– Zn
– CuSO4
– NaCl
– H2O
– Al2(SO4)3
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The Mole – a word that means a #
Other words that mean #s: One dozen =
12
One gross = 144
One score = 20
One ream = 500
One MOLE = 6.02 x 1023
602000000000000000000000
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Where does Avogadro’s Number come from?
A formula:
M = NAmC
The mass of 1 carbon-12 atom is 1.99 x 10-23 g
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Avogadro’s Number
Avogadro’s Number - 6.02 x 1023 particles in 1 mole 1 mole of 12C has a mass of 12 g.
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Mole Conversions
Moles tell you how many atoms you have, AND how much mass in grams you have.
We use moles to convert from atoms and grams.
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Mole Conversion Factors
There are 4 possible conversion factors for mole conversions:– Show your work -use a conversion factor every time
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Mole Diagram – Conversion Factors
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Using your calculator
To Enter 6.02 x 1023 into your calculator, use the EE button, so it would appear as 6.02E23. Practice with the two following examples
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Examples:
If you have 4.25 x 1022 atoms of Al, how many moles do you have?
If you have 0.37 moles of Al, how many atoms do you have?
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Mole Examples (lol)
If you have 8.64g of Mg, how many moles do you have?
If you have 1.23 moles of Phosphorous, how many grams do you have?
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Mole Relationships
One mole of:– atoms– ions– molecules
contains Avogadro’s number of those particles.
One mole of:– molecules or formula units
contains Avogadro’s number times the number of atoms or ions of each element in the compound.