Chapter 10 “Chemical Quantities”. Yes , you will need a calculator for this chapter!. Pre-AP Chemistry Charles Page High School Stephen L. Cotton. Section 10.1 The Mole: A Measurement of Matter. OBJECTIVES: Describe methods of measuring the amount of something.
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Chapter 10“Chemical Quantities”
Yes, you will need a calculator for this chapter!
Charles Page High School
Stephen L. Cotton
What is the mole?
We’re not talking about this kind of mole!
= 2 shoelaces
= 12 oranges
= 144 pencils
= 500 sheets of paper
3 atoms of oxygen
12 (3 x 4) atoms of oxygen
3 total ions (1 Ca2+ ion and 2 Cl1- ions)
2 total ions (1 Na1+ ion and 1 OH1- ion)
5 total ions (2 Al3+ + 3 SO42- ions)
2.75 x 1024 molecules
0.0975 mol (or 9.75 x 10-2)
4.44 x 1024 atoms C
- The amu was one twelfth the mass of a carbon-12 atom.
28.1 grams C
1 mol Mg
8.72 x 1022 atoms Li
13.6 grams U
Calculate the formula mass of magnesium carbonate, MgCO3.
24.3 g + 12 g + 3 x (16.00 g) =
Thus, 84.3 grams is the formula mass for MgCO3.
= 78 g/mol gram formula mass
= 92 g/mol gram molecular mass
= 12 g/mol gram atomic mass
= 164 g/mol gram formula mass
= 180 g/mol gram molecular mass
= 149 g/mol gram formula mass
- To change between grams of a compound and moles of a compound.
(Solution on next slides)
- They are difficult to weigh (or mass).
a) Temperature and b) Pressure
- is abbreviated “STP”
- Called the molar volume
= 103 L
= 0.253 mol
= 12.3 L
- for a gas the units will be: g / L
D = 44g/22.4L = 1.96 g/L
D = 16g/22.4L = 0.714 g/L
modify: D = m/V to show:
m = D x V
= 44.0 g/mol
= 64.0 g/mol
a) 1 mole
b) molar mass (in grams/mol)
c) 6.02 x 1023 representative particles (atoms, molecules, or formula units)
d) 22.4 L of gas at STP
Thus, we can make conversion factors from these 4 values!
x 100 % = percent
29.0 g Ag
X 100 = 87.1 % Ag
33.3 g total
Total = 100 %
4.30 g S
X 100 = 12.9 % S
33.3 g total
85.7% C, 14.3 % H
23.1% Al, 15.4% C, and 61.5 % O
Empirical formula: the lowest whole number ratio of atoms in a compound.
Molecular formula: the true number of atoms of each element in the formula of a compound.
Formulas for ionic compounds are ALWAYS empirical (the lowest whole number ratio = cannot be reduced).
Formulas for molecular compoundsMIGHT be empirical (lowest whole number ratio).
(Lowest whole number ratio)
= this is already the lowest ratio.
- the percentage become grams (75.1% = 75.1 grams)
Now divide each value by the smallest value
=C1H5N1 which is = CH5N
Note page 313 – Gas Chromatography used for chemical analysis
End of Chapter 10