1 Chapter 10 Chemical Quantities 10.4 Calculations Using Molar Mass Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

2 Molar mass factors are used to convert between the grams of a substance and the number of moles. Calculations Using Molar Mass Grams Molar mass factor Moles

3 Aluminum is used to build lightweight bicycle frames. How many grams of Al are 3.00 mol Al? Molar mass equality: 1 mol Al = g Al Setup with molar mass as a factor: 3.00 mol Al x g Al = 80.9 g Al 1 mol Al molar mass factor for Al Moles to Grams

4 Learning Check Allyl sulfide C 6 H 10 S is a compound that has the odor of garlic. How many moles of C 6 H 10 S are in 225 g C 6 H 10 S? Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

5 Calculate the molar mass of C 6 H 10 S. 1mol C6H10S = (6 x 12.01) + (10 x 1.008) + (1 x 32.07) = g/mol Set up the calculation using a mole factor. 225 g C 6 H 10 S x 1 mol C 6 H 10 S g C 6 H 10 S molar mass factor(inverted) = 1.97 mol C 6 H 10 S Solution

6 Grams, Moles, and Particles A molar mass factor and Avogadro’s number convert Grams to particles molar mass Avogadro’s number (g mol particles) Particles to grams Avogadro’s molar mass number (particles mol g)

7 Learning Check How many H 2 O molecules are in 24.0 g H 2 O? 1) 4.52 x ) 1.44 x ) 8.02 x 10 23

8 Solution How many H 2 O molecules are in 24.0 g H 2 O? 3) 8.02 x g H 2 O x 1 mol H 2 O x x H 2 O molecules g H 2 O 1 mol H 2 O = 8.02 x H 2 O molecules

9 Learning Check If the odor of C 6 H 10 S can be detected from 2 x g in one liter of air, how many molecules of C 6 H 10 S are present?

10 Solution If the odor of C 6 H 10 S can be detected from 2 x g in one liter of air, how many molecules of C 6 H 10 S are present? 2 x g x 1 mol x x molecules g 1 mol = 1 x 10 9 molecules C 6 H 10 S