Chapter 10 Chemical Quantities 10.1 The Mole: A Measurement of Matter 10.2 Mole-Mass and Mole-Volume Relationships 10.3 Percent Composition and Chemical Formulas Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Mole-Mass Relationship We can use the molar mass of a substance to convert from moles to mass Remember the molar mass is the mass of 1 mole of that substance SO3 = 80.07 g/mol = 80.07 g SO3 1 mol SO3

Using this relationship, we can easily convert a mole amount to a mass amount How many grams is there in a 0.750 mole sample of SO3?

We can also convert a mass amount to a mole amount How many moles is there in a 28.5 gram sample of SO3?

The Mole-Volume Relationship We can also make conversion between moles and volume, if the conditions are STP Standard temperature (0 °C) and pressure (1 atm)

The Mole-Volume Relationship Notice that the volumes of one mole of different solid and liquid substances are not the same. The volumes of one mole of glucose (blood sugar) and one mole of parachlorobenzene (moth crystals) are much larger than the volume of one mole of liquid water. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The volume of solid and liquid substances may vary when the substance is changed However, gases are unique in that they have a constant volume, regardless of the substance, at STP. 1 mole of gas at STP = 22.4 L This can only be used for a gas We can use this new relationship to do conversions So when you read the problem it must mention at STP to use the last equality

Example 1: How many liters is present when you have 0 Example 1: How many liters is present when you have 0.60 mol of SO2 at STP? Using the various relationships to moles, we can also solve problems related to the density of gases

Example 2: How many moles of O2 gas are in 78.4 liters of O2 at STP?

Using the various relationships to moles, we can also solve problems related to the density of gases Density = Mass Volume Example: The density of a gaseous compound containing carbon and oxygen is found to be 1.964 g/L at STP. What is the molar mass of the compound?

What if you were given a mass of a substance and had to find either the # of representative particles or volume? You would have to do a 2 step conversion where the mole is your “middle” man Example 1: How many molecules of H2O are there in 15.2 g of H2O? 5.10x1023 molecules of H2O

The Mole-Volume Relationship The mole is at the center of your chemical calculations. To convert from one unit to another, you must use the mole as an intermediate step. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Example 2: How many liters of SO2 at STP are in 5 Example 2: How many liters of SO2 at STP are in 5.55 x 1021 molecules of SO2? 0.207 L of SO2

Example 3: How many grams are in 56.0 L of sulfur trioxide at STP? 200 grams of SO3

Welcome to Mole Island 1 mol = mass 1 mole = 22.4 L @ STP 1 mol = 6.02 x 1023 particles