Chemistry Notes - The Mole

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CHEMISTRY I NOTES ~ THE MOLE
NOTE: Vocabulary terms are in boldface and underlined. Supporting details are in italics.
I.
MOLES
A. SI unit of chemical quantity = the mole (abbreviated mol)
B. The mole is a counting unit
23
1 MOLE = 6.02 x 10
representative particles
(representative particles = ATOMS, IONS, MOLECULES, & FORMULA UNITS)
23
23
6.02 x 10
atoms = 1 mol atoms
6.02 x 10
molecules
= 1 mol molecules
23
23
6.02 x 10
ions
= 1 mol ions
6.02 x 10
formula units = 1 mol f.units
23
C. 6.02 x 10
= Avogadro’s number (named after Amedeo Avogadro, 1776–1856)
D. example problems:
16
E1) How many moles of Ca are in 9.00 x 10
atoms of Ca?
16
-7
9.00 x 10
atoms Ca x ____1 mol Ca______ = 1.50 x 10
mol Ca
23
6.02 x 10
atoms Ca
30
2-
E2) How many moles of sulfide ions are in 4.14 x 10
ions of S
?
30
2-
6
2-
4.14 x 10
ions S
x
___1 mol S
_
= 6.88 x 10
mol S
23
2-
6.02 x 10
ions S
E3) How many molecules are in 0.0221 mol O
?
2
23
22
0.0221 mol O
x
6.02 x 10
molecules O
= 1.33 x 10
molecules O
2
2
2
1 mol O
2
E. Finding the number of atoms in a compound—look at the subscripts
example problems:
E4) How many hydrogen atoms are in 0.89 mol water?
23
24
0.89 mol H
O x 6.02 x 10
molecules H
O x
2 H atoms
= 1.1 x 10
H atoms
2
2
1 mol H
O
1 molecule H
O
2
2
+
E5) How many Na
ions are found in 0.129 mol of Na
PO
?
3
4
23
+
23
0.129 mol Na
PO
x 6.02 x 10
f. units x 3 Na
ions____ = 2.33 x 10
f. units Na
PO
3
4
3
4
1 mol Na
PO
1 f. unit Na
PO
3
4
3
4
II.
Masses: GAM, GMM, GFM
A. GAM = gram atomic mass
1) the atomic mass (listed on the periodic table) written in grams
1 atom Xe = 131.30 amu
& 1 mol Xe = 131.30 g & GAM of Xe = 131.301 g
2) these numbers are usually rounded to 0.1 (tenths)
B. GMM = gram molecular mass
1) the sum of all masses of atoms in a molecular compound
1 molecule Cl
= 70.9 amu & 1 mol Cl
= 70.9 g & GMM Cl
= 70.9 g
2
2
2
2) example:
E6) Find the GMM of methane, CH
.
4
CH
= 1(12.0) + 4(1.0) = 12.0 + 4.0 = 16.0 g
4
C. GFM = gram formula mass
1) the mass of one mole of ionic compound
1 f.unit NaCl = 58.4 amu & 1 mol NaCl = 58.4 g & GFM NaCl = 58.4 g
2) example:
E7) Find the GFM of calcium hydroxide, Ca(OH)
.
2
Ca(OH)
= 1(40.1) + 2(16.0) + 2(1.0) = 74.1 g
2

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