The Mole

Chapter 11

Measuring Matter

Section 11.1

How much is a mole?

• Count large # of items is easier when you use counting units like the dozen

• Chemists use a counting unit called the mole

How is a mole used in chemistry?

• Mole (mol) is SI base unit used to measure amount of substance

1 mole = Avogadro’s # = 6.022 x 1023 RP• Representative particles (RP)

= atoms

= molecules

= FU

= electrons

= ions

Relate a mole to common counting units

• 1 dozen eggs = 12 eggs

• 1 pair of shoes = 2 shoes

• 1 ream of paper = 500 sheets of paper

• 1 lb of sugar = 16 ounces of sugar

• 1 Liter of HCl = 1000 mL of HCl

1 Mole of Representative Particle (RP)

Molecule of water

Atom of Cu

FU of NaCl

How many roses are in 3 ½ dozens?

Conversion factor: 12 roses/1 dozen

3.5 dozen x 12 roses/1 dozen = 42 roses

Convert moles # RP

? RP = given moles x 6.02 x 1023 RP

1 mole

Example

? mole = given RP x 1 mole 6.02 x 1023 RP

= 2.65 x 1024 FU ZnCl2 x 1 mole ZnCl2 6.02 x 1023 FU ZnCl2

= 4.40 moles ZnCl2

Convert # RP moles

? mole = given RP x 1 mole 6.02 x 10 23 RP

ExampleConversion factor: 6.02 x 1023 RP/ 1 mol

? RP = given moles x 6.02 x 10 23 RP

1 mole

= 3.5 moles sucrose x 6.02 x 1023 molecules sucrose

1 mole sucrose

=2.11 x 1024 molecules sucrose

Practice

Determine the # of atoms in 2.50 mol Zn.

1.51 x 1024 atoms Zn

Given 3.25 mol AgNO3, determine # FU

1.96 x 1024 formula units AgNO3

Calculate # molecules in 11.5 mol H2O

6.92 x 1024 molecules H2O

More Practice

How many moles contain 5.75 x 1024 atoms of Al?

9.55 mol AlHow many moles contain 3.75 x 1024

molecules CO2?

6.23 mol CO2

How many moles contain 3.58 x 1023 formula units ZnCl2?

0.595 mol ZnCl2

Homework

p. 311-312 from textbook1-4

10

Due tomorrow

Mass and the Mole

Section 11.2

Relate the mass of an atom to the mass of a mole of atoms

1 dozen eggs and 1 dozen limes are not equal masses

Why? Because they are different compositions and size

Avogadro’s Number

6.022 x 1024 Representative Particles

Representative Particles =

ions,

atoms,

molecules,

electrons,

FULorenzo Romano Amedeo Carlo Avogadro, conte di Quaregna e di Cerreto (1776 - 1856) Photo from http://www.bulldog.u-net.com/avogadro/avoga.html

Mole to Atom?

• 1 mole = 6.022 x 1024 atoms

• 1 mole = 6.022 x 1024 molecules

• 1 mole = 6.022 x 1024 ions

• 1 mole = 6.022 x 1024 electrons

• 1 mole = 6.022 x 1024 Formula Units (FU)

Calculate mole grams

? Grams = given moles x grams from PT

1 mole

Calculate the mass of an element when given # of atoms of element

? grams = atoms x 1 mol x g from PT

6.02 x 1023atoms 1 mol

Calculate # of atoms of element when given mass of element

? Atoms = grams x 1 mol x 6.02 x 1023atoms g from PT 1 mol

Homework

• Pages 316-318 (12-14) from the textbook

• Due tomorrow

Moles of Compounds

Section 11.3

Recognize the mole relationship shown by a chemical formula

Calculate the molar mass of a compound

• Add the atomic masses from the periodic table together

• Ex: Find the molar mass for MgCl2Molar mass = massMg + 2 (massCl)

= 24.305 g + 2(35.453 g)

= 24.305 g + 70.906 g

= 95.211 g MgCl2

Calculate # moles of compound from given mass of compound

Calculate mass of compound from given # moles of compound

Determine # atoms or ions in a mass of a compound

Empirical & Molecular Formulas

Section 11.4

Explain what is meant by the % composition of a compound

Determine the empirical & molecular formulas for compound from mass % & actual mass data

The formula for a hydrate

Section 11.5

What is a hydrate?

How does its name reflects its composition?

Determine the formula for a hydrate from laboratory data