Chemical Quantities

Chapter 12

What do all these things have in common with the mole?

1 dozen 1 pair 1 six pack

Answer: They all represent quantities

Warm-up #1

Measuring MatterWhat is a mole?

The mole (mol) is the SI base unit used to measure the amount of a substance.

1 mol = 6.02x1023 representative particles6.02x1023 is called Avogadro’s number

Representative particles are the units used in these conversions

Particles Names Atoms, formula units (ionic compounds), molecules (covalent compounds)

Everything Leads to the Mole

1mole = 6.02 x 1023 particles1mole = molar mass

1mole = 22.4 L at STP

Mole to Particle Conversions

How many molecules of water are there in 2.4 moles of water?

How many moles of copper contain 3.5 x 1018 copper atoms?

1mole = 6.02 x 1023 particles

Warm-up #2

What is the mass of this bicycle given the mass of it’s individual parts?

1wheel = 0.5 kg, 1frame = 5 kg, 1seat = 0.2 kg,

1 set of handlebars = 1kg

Mass and the Mole

The mass of one mole of a substance is unique to that substance and is based on the sum of the atomic masses of the elements in that substance.

1 mole of lead = 207.2g 1 mole of water = 18.0g 1 mole of copper = 63.6g

Mass of H2O = mass of two hydrogen atoms + mass of one oxygen atom

Calculating Molar Mass

ElementsThe molar mass of elements is equal to their atomic mass from the periodic table.

Example: 1 mole of Fe atoms = 55.847g

CompoundsThe molar mass of compounds is equal to the sum of the atomic masses of the individual elements in that compound.

Example: 1 mole of Fe2(SO4)3=

(2 x 55.847) + (3 x 32.066) + (12 x 15.999) = 401.662

Mole-Mass Conversions

Unlike mole-particle conversions where the conversion factor is always 1mole = 6.02 x 1023 particles, each mole-mass conversion factor is unique to the substance involved.

Convert 2.3 moles of sodium (Na) to grams of Na

Convert 10.0 g of CO2 to moles of CO2

Warm-up #3

What contains more representative particles, a mole of Fe2(SO4)3 or a mole of H2O?

Volume and the Mole

According to Avogadro, the mass of one mole of a gas at STP is always 22.4L regardless of the gas’ identity.

STP = Standard Temperature and Pressure (0oC and 1 atm)

Mole-Volume Conversions

How many moles of CO are contained in 1.8L of CO gas?

How many Liters of SO3 are represented by 0.5 moles of SO3 gas?

Multi-Step Conversions

1mole = 6.02 x 1023 particles1mole = molar mass

1mole = 22.4 L at STP

What is the mass of 1.0 x 1019 atoms of Aluminum?

Warm-up #4

Examine the reaction above. Using the parts below, how many of the product could be made?

+ 4

What is Stoichiometry?

Stoichiometry is the study of quantitative relationships between amounts of reactants used and products formed by a chemical reaction.

Practical Applications of Stoichiometry

In a spacecraft, the carbon dioxide exhaled by astronauts can be removed by its reaction with lithium hydroxide, LiOH, according to the following chemical equation.

CO2(g) + 2LiOH(s) Li2CO3(s) + H2O(l)

How many moles of lithium hydroxide are required to react with 20 mol of CO2, the average amount exhaled by a person each day?

Strategy – Relate everything to the mole

The mole is the common thread that links reactants to products.

1CO2(g) + 2LiOH(s) 1Li2CO3(s) + 1H2O(l)

Mole Ratios

molLiOH

molCO

2

1 2

32

2

1

1

COmolLi

molCOOmolH

molCO

2

2

1

1

321

2

COmolLi

molLiOHOmolH

molLiOH

21

2

Mole Super Highway

Stoichiometry Practice Problems

2H2(g) + O2(g) 2H2O(l)

How many moles of water can be formed from 3 moles of oxygen?

How many grams of water can be formed from 8.0 grams of hydrogen gas at?

Warm-up #5

Ingredients2 1/4 cups all-purpose flour 1 teaspoon baking soda 1 teaspoon salt 1 cup (2 sticks) butter, softened 3/4 cup granulated sugar 3/4 cup packed brown sugar 1 teaspoon vanilla extract 2 large eggs 2 cups (12-oz. pkg.) 1 cup chopped nuts

Yield: 24 cookies

How many cookies can be made if I only have 1 stick of butter and 1 cup of sugar (and the exact quantity of the other ingredients in the recipe)?