Monday, March 17th: “A” Day Tuesday, March 18th: “B” Day

AgendaCh. 6 TestsBegin Chapter 7: “The Mole and

Chemical Composition” In-Class Assignments:

Practice pg. 228: #1-4Practice pg. 229: #1-4Concept Review: “Avo’s Number/Molar

Conversions”Homework: pg. 21/22 worksheet MUST SHOW WORK!

Ch. 6 Tests“Covalent Compounds”

Class Average Grade(out of 65)

Average Percentage

2A 54.35 83.63%4A 55.80 85.85%1B 58.11 89.40%3B 60.45 93.00%

Start Section 7.1: “Avogadro’s Number and Molar

Conversions”Atoms, ions, and molecules are very small, so

even tiny samples have huge numbers of particles.

Scientists use the mole to make counting such large numbers easier.

Mole: the SI unit for amount; the number of atoms in exactly 12 grams of carbon-12.

The Mole is a Counting UnitThe mole is used to count out a given number of

particles, whether they are atoms, molecules, formula units, ions, or electrons.

The mole is just one kind of counting unit:

1 dozen = 12 objects1 roll = 50 pennies1 hour = 3,600 seconds1 pair = 2 items 1 mole = 6.022 1023 particles

Avogadro’s Number & the Mole

The number of particles in a mole is called Avogadro’s Number.

Avogadro’s number is 6.022 1023; the number of atoms or molecules in 1.000 mole

Lorenzo Romano Amedeo Carlo AvogadroBorn in Turin, Italy, on August 9th, 1776.

Conversion Factors are Equivalent to 1The definition of one mole is:

6.022 1023 particles = 1 mol

From this definition, we get 2 conversion factors:6.022 X 1023 particles = 1

1 mol

_____1 mol________ = 16.022 X 1023 particles

Use the Conversion Factor that Cancels Out the Known Units

Because a conversion factor is equal to 1, it can multiply any quantity without changing the value.

Only the units are changed.When solving problems, the unit that you know

goes on the bottom of the fraction.

You Can use Conversion Factors to Change from One Unit to Another

(Dimensional Analysis)Example #1: How many eggs are there in 5 dozen?1.Start with what you know: 5 dozen2.Multiply by a conversion factor to change

dozen number of eggs:

5 dozen X 12 eggs = 60 eggs 1 dozen

Example #2: If you have 548 plain white socks, how many pairs can you make?

1. Start with what you know: 548 socks2.Multiply by a conversion factor to change socks pairs of socks:548 socks X 1 pair =

2 socks 274 pairs

You Can use Conversion Factors to Change from One Unit to Another

(Dimensional Analysis)

Changing Moles ParticlesSample Problem A, pg 228

Find the number of molecules in 2.5 mol of sulfur dioxide, SO2.

1.Start with what you know: 2.5 mol SO2

2.Multiply by a conversion factor to change moles molecules:

2.5 mol SO2 X 6.022 X 1023 molecules SO2 =

1 mole SO2

1.5 X1024 (2 sig figs) molecules SO2

Changing Moles Particles Practice #1

How many particles are there in 2.45 X 10-6 mol of nickel, Ni(II) selenide, NiSe?

1. Start with what you know: 2.45 X 10-6 mol NiSe2. Multiply by conversion factor to change

moles particles:2.45 X 10 -6 mol NiSe X 6.022 X 1023 particles NiSe =

1 mole NiSe

1.48 X 1018 particles (3 sig figs) NiSe

Changing Moles Particles Practice #2

How many atoms are there in 4.3 moles of tungsten, W?

1. Start with what you know: 4.3 moles W2. Multiply by conversion factor to change

moles atoms:4.3 mol W X 6.022 X 1023 atoms W =

1 mol W

2.6 X 1024 atoms W(2 sig figs)

So far, we’ve been changing moles particles

Do you think we can go the other way, and change

particles moles?Of course we can, and that’s

what we’re going to do!

Changing Particles MolesSample Problem B, pg. 229

A sample contains 3.01 X 1023 molecules of sulfur dioxide, SO2. Determine the amount in moles.

1. Start with what you know: 3.01 X 1023 molecules SO2

2. Multiply by conversion factor to change molecules moles:

3.01 X 1023 molecules SO2 X __1 mole SO2______

6.022 X 1023 molecules SO2

0.500 mole SO2 (3 sig figs)

Changing Particles Moles Practice #1

How many moles are equivalent to 6.93 X 1023 thallium atoms, Tl?

1. Start with what you know: 6.93 X 1023 Tl atoms2. Multiply by conversion factor to change

atoms moles:6.93 X 1023 Tl atoms X 1 mole Tl =

6.022 X 1023 Tl atoms

(3 sig figs) 1.15 mole Tl

Changing Particles Moles Practice #2

How many moles are equivalent to 7.95 X 1024 copper (II) chloride, CuCl2, formula units?

1. Start with what you know: 7.95 X 1024 CuCl2 formula units

2. Multiply by conversion factor to change formulaunits moles:

7.95 X 1024 form. unit CuCl2 X ____1 mole_CuCl2___ 6.022 X 1023 form. unit CuCl2

13.2 mol CuCl2 (3 sig figs)

In-Class Assignments/HomeworkPractice pg. 228: #1-4 Practice pg. 229: #1-4

Homework:Practice Worksheets, pg. 21/22Concept Review: Avogadro’s Number and Molar

Conversions” #1-5

You must SHOW WORK to get credit!