Chapter 8 Molecular & Formula Masses. How many minutes does it take light to reach us from the sun which is 93,000,000 miles distant.

Chapter 8

Molecular & FormulaMasses

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 AC20H30O

Determine the Molecular Mass of Vitamin AC20H30O

20 x 12.0 = 240.030 x 1.0 = 30.01 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 PhosphateCa3(PO4)2

3 x 40.1 = 120.32 x 31.0 = 62.08 x 16.0 = 128.0 = 310.3 amu

Homework

• Molecular and Formula Mass Worksheet.

• Don’t forget to show your work on your calculations.