Chapter 11 Notes, Part IWhat is a mole?

One Step Problems

What is a mole?

• A furry, burrowing woodland creature, revered by many and adored by all?

Maybe!• But not really in chemistry!

A Mole...

• is a unit of measurement that tells how many particles of something you have!

• much like a dozen (12), a gross (144) or a ream (500) is just a unit that groups smaller numbers into big ones...but its a big one; a REALLY big one!

1 mole = 6.02 x 1023 particles!

(that’s a lot of flowers!)

What are particles?

• Particles could be anything, but because of the size of the number, we usually mean

Atoms,

molecules, or

formula units.

Avogadro’s Number

• The number 6.02 x 1023 is called Avogadro’s number.

• This is due to Amadeo Avagadro’s research leading to the discovery, not the discovery of the number itself.

It is a little known fact that Avogadro was voted It is a little known fact that Avogadro was voted his class’s most likely to have a scientific his class’s most likely to have a scientific

discovery and most likely to look really creepy.discovery and most likely to look really creepy.

Obj. 1…Formula vs. Molecular Obj. 1…Formula vs. Molecular MassMass

• Formula mass = total mass of ionic compoundsFormula mass = total mass of ionic compounds

- starts with a metal- starts with a metal

• Molecular mass = total mass of molecular compoundsMolecular mass = total mass of molecular compounds

- starts with a non-metal- starts with a non-metal

• To calculate…To calculate…

- find mass of each element on P.T. (whole #s)- find mass of each element on P.T. (whole #s)

- multiply mass by subscript and/or coefficient- multiply mass by subscript and/or coefficient

- add all masses together for total mass- add all masses together for total mass

Obj. 1 cont…Obj. 1 cont…

• Practice…Practice…

AlAl22(SO(SO44))33

27 x 2 = 5427 x 2 = 54

32 x 3 = 9632 x 3 = 96

16 x 12 = 19216 x 12 = 192

54 + 96 + 192 = 54 + 96 + 192 = 342 amu342 amu

formula massformula mass

SS33FF66

32 x 3 = 9632 x 3 = 96 19 x 6 = 11419 x 6 = 114

96 + 114 = 96 + 114 = 210 amu210 amu

molecular massmolecular mass

• more practice…more practice…

Obj. 1 cont…Obj. 1 cont…

3CaC3CaC22OO44

40 x 3 = 12040 x 3 = 120

12 x 6 = 7212 x 6 = 72

16 x 12 = 19216 x 12 = 192

120 + 72 + 192 = 120 + 72 + 192 =

384 amu384 amu

OROR 40 x 1 = 4040 x 1 = 40

12 x 2 = 2412 x 2 = 24

16 x 4 = 6416 x 4 = 64

40 + 24 + 64 = 40 + 24 + 64 = 128 128 x 3 =x 3 =

384 amu384 amu

CuSOCuSO44 5H 5H22OO

two compounds chemically bonded together… two compounds chemically bonded together… NOTNOT multiply!!! multiply!!!

6464 3232 6464 1010 8080

64 + 32 + 64 + 10 + 80 = 64 + 32 + 64 + 10 + 80 = 250 amu250 amu

• recall that one precall that one p+ + / n/ n00 = 1.67 x 10 = 1.67 x 10-24-24 grams grams

• therefore…one mole of nucleons = 1 gramtherefore…one mole of nucleons = 1 gram

Obj. 2 cont…Obj. 2 cont…

** 1.67E ** 1.67E -24-24 x 6.02E23 = 1 x 6.02E23 = 1

• amu = g/moleamu = g/mole

• one mole = one mole =

~~ 6.02 x 10 6.02 x 102323 atoms, molecules or ions in a compound atoms, molecules or ions in a compound

~~ molar mass of compound / element molar mass of compound / element

molar massmolar massatomic massatomic mass

~~ 22.4 liters of any gas at 22.4 liters of any gas at STPSTP (standard temp. and pressure)(standard temp. and pressure)

00°C°C 760 mmHg760 mmHg101.3 kPa101.3 kPa

1 atm1 atm273K273K

Obj. 3-7…Mole ConversionsObj. 3-7…Mole Conversions

MoleMoleLitersLiters

# of atoms/ # of atoms/ moleculesmolecules

GramsGramsX by 22.4X by 22.4

by 22.4by 22.4

by molar mass by molar mass

X by molar mass X by molar mass

X by 6.02 x 10X by 6.02 x 102323 by 6.02 x 10by 6.02 x 102323

• use ‘mole map’ to solve mole conversions…use ‘mole map’ to solve mole conversions…** going ** going away away from moles = x from moles = x

** going ** going toward toward moles = moles = ÷÷

Obj. 3-7 cont…Obj. 3-7 cont…• Practice, practice, practice…Practice, practice, practice…

2.0 moles He = ____________ atoms He 2.0 moles He = ____________ atoms He

2.0 moles x 6.02E23 = 2.0 moles x 6.02E23 =

1.2 x 101.2 x 102424

2.0 moles H2.0 moles H22O = ____________ grams HO = ____________ grams H22O O

2.0 moles x 18 = 2.0 moles x 18 =

36 36

22 1616 = 18= 18

67.2 liters O67.2 liters O22 = ____________ moles O = ____________ moles O22

67.2 liters 67.2 liters ÷÷ 22.4 = 22.4 =

3.00 3.00

27 grams H27 grams H22O = ____________ moles HO = ____________ moles H22O O

22 1616 = 18= 18

27 grams 27 grams ÷÷ 18 = 18 =

1.5 1.5

Obj. 3-7 cont…Obj. 3-7 cont…• more practice…more practice…

3.61 x 103.61 x 102424 molecules NaCl = ____________ moles NaCl molecules NaCl = ____________ moles NaCl

3.61 x 103.61 x 102424 molecules molecules ÷÷ 6.02 x 10 6.02 x 102323 = =

6.00 6.00

5.0 moles CO5.0 moles CO22 = ____________ liters CO = ____________ liters CO22

5.0 moles 5.0 moles xx 22.4 = 22.4 =

110110

**** 3.61 x 103.61 x 102424 molecules CO molecules CO22 = ____________ grams CO = ____________ grams CO2 2 ** **

3.61 x 103.61 x 102424 molecules molecules ÷÷ 6.02 x 10 6.02 x 102323 = 6 moles x = 6 moles x

122 3232 = 44= 44

44 grams =44 grams =

264264

Practice Problem #1

• How many moles are in 2.57 x 10How many moles are in 2.57 x 102525 atoms He?atoms He?

Practice Problem #2

• How many molecules of CO2 are in 25.3 moles?

Practice Problem #3

• How many moles of O2 are in 29.3L of O2 gas?

Practice Problem #4

• If you have 3.6 moles of N2O (Nitrous oxide) how many liters would you have?

Practice Problem #5

• How many grams of iron are in 3.5 moles?

Practice Problem #6

• How many moles of Na2O are in 355.1g?