Monday, March 17th: A Day Tuesday, March 18th: B DayAgendaCh. 6 TestsBegin Chapter 7: The Mole and Chemical CompositionIn-Class Assignments:Practice pg. 228: #1-4Practice pg. 229: #1-4Concept Review: Avos Number/Molar ConversionsHomework: pg. 21/22 worksheet MUST SHOW WORK!
Ch. 6 TestsCovalent Compounds
ClassAverage Grade(out of 65)Average Percentage2A54.3583.63%4A55.8085.85%1B58.1189.40%3B60.4593.00%
Start Section 7.1: Avogadros Number and Molar ConversionsAtoms, 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
Avogadros Number & the MoleThe number of particles in a mole is called Avogadros Number.
Avogadros 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 = 11 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?Start with what you know: 5 dozenMultiply 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 socksMultiply by a conversion factor to change socks pairs of socks:548 socks X 1 pair = 2 socks 274 pairsYou 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.Start with what you know: 2.5 mol SO2Multiply 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 #1How many particles are there in 2.45 X 10-6 mol of nickel, Ni(II) selenide, NiSe?
Start with what you know: 2.45 X 10-6 mol NiSeMultiply 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 #2How many atoms are there in 4.3 moles of tungsten, W?
Start with what you know: 4.3 moles WMultiply 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, weve been changing moles particlesDo you think we can go the other way, and changeparticles moles?Of course we can, and thats what were going to do!
Changing Particles MolesSample Problem B, pg. 229A 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 SO2Multiply by conversion factor to change molecules moles:3.01 X 1023 molecules SO2 X __1 mole SO2______ 6.022 X 1023 molecules SO20.500 mole SO2 (3 sig figs)
Changing Particles Moles Practice #1How many moles are equivalent to 6.93 X 1023 thallium atoms, Tl?1. Start with what you know: 6.93 X 1023 Tl atomsMultiply 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 #2How 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 unitsMultiply 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: Avogadros Number and Molar Conversions #1-5
You must SHOW WORK to get credit!