Transcript Chapter 8 - Molecular and Formula Masses

Chapter 8
Molecular & Formula
Masses
Atomic mass
• The atomic mass is the average mass of
an atom.
When using
atomic masses
make sure to
round to at least
one decimal
place.
What is the
atomic mass of
actinium (Ac)?
227.0278
227.0
What is the
atomic mass of
hydrogen (H)?
1.00794
1.0
What is the mass
of hydrogen (H2)?
2.0
Vitamin A: C20H30O
• The first of the 13 vitamins to be discovered,
it plays a vital role in the growth and repair of
body tissues, and is particularly important in
maintaining good eyesight and healthy skin,
as well as aiding in bone and teeth formation.
• Vitamin A-rich foods include: Liver, sweet
potatoes, carrots, mangoes, spinach,
cantaloupe, dried apricots, milk, egg yolks,
mozzarella cheese.
Determine the
Molecular Mass of
Vitamin A
C20H30O
20 x 12.0 = 240.0
30 x 1.0 = 30.0
1 x 16.0 = 16.0
= 286.0 amu
H
H2O
NaCl
• H is an atom and it would therefore have an
atomic mass.
• H2O is a molecule and it would therefore have
a molecular mass.
• NaCl is neither an atom or a molecule and
would therefore have a formula mass.
Formula Mass
• The formula mass is the mass of an ionic
compound.
• An ionic compound is formed from a
combination of metals and nonmetals.
• Formula masses are calculated the same
as molecular masses.
Determine the
Formula Mass of
Calcium Phosphate
Ca3(PO4)2
3 x 40.1 = 120.3
2 x 31.0 = 62.0
8 x 16.0 = 128.0
= 310.3 amu
Homework
• Molecular and Formula Mass Worksheet
(due in two days).
• Don’t forget to show your work on your
calculations.