Unformatted text preview: MOLECULAR WEIGHT
AND MOLAR MASS
Molecular weight is the sum of the
atomic weights of all atoms in the
molecule. Molar mass = molecular weight in
grams What is the molar mass of
ethanol, C 2H6O? Tylenol
Tylenol 1 mol contains
2 mol C (12.01 g C/1 mol) = 24.02 g C
6 mol H (1.01 g H/1 mol) = 6.06 g H
1 mol O (16.00 g O/1 mol) = 16.00 g O
TOTAL = molar mass = 46.08 g/ mol • Formula = C8H9NO2
• Molar mass = 151.2 g/mol How many moles of alcohol are
there in a “standard” can of beer if
there are 21.3 g of C 2H6O? How many molecules of alcohol
How
molecules of
are there in a “standard” can of
beer if there are 21.3 g of C 2H6O? How many atoms of C are there in
are
a “standard” can of beer if there are
21.3 g of C 2H6O? (a) Molar mass of C 2H6O = 46.08 g/mol
(b) Calc. moles of alcohol We know there are 0.462 mol of C 2H6O. We know there are 2.78 x 10 23 molecules.
Each molecule contains 2 C atoms.
Therefore, the number of C atoms is 21.3 g • 1 mol
= 0 .462 mol
46.08 g 0.462 mol • 6.022 x 10 23 molecules
1 mol = 2.78 x 10 23 molecules 2.78 x 10 23 m olecules • = 5.57 x 10 23 C atoms Page 1 2 C atoms
1 molecule ...
View
Full Document
 Spring '08
 Staff
 Chemistry, Atom, Mole, Molecule, Atomic mass unit

Click to edit the document details