The Mole A Counting Unit 09 You WILL NEED your calculators from now on!! Rev 10/12/09.

The MoleThe Mole

A Counting Unit

‘ 09

You WILL NEED your You WILL NEED your calculators from now on!!calculators from now on!!

Rev 10/12/09

Other Counting Units

1 Dozen =12 things

1 Pair =2 things

1 Gross = 144 things (a dozen dozens)

1 mole (mol)=

602,000,000,000,000,000,000,000 things

= 6.02 x 1023 things What could you possibly measure that is

made up of so many things?

Yes, we do abbreviate a 4 letter word with a 3 letter word – but not just me – the whole world does!

Random FYI…

If you had a mole’s worth of rice (meaning 6.02 x 1023 grains of rice, it would weigh just as much as if EVERY PERSON on the planet had a MILLION cars!!!!!

So why in the WORLD would we want to work with such a HUGE quantity?

Because atoms are so small!!!!

Moles are used to represent very small particles like the number of:

AtomsMolecules Formula units

Moles enable chemists to

“count by weighing”

Now remember our rice story… every person with a million cars… now think about that same amount of hydrogen… guess how much it might weigh… H2=2

grams!

1 mole of an atom = It’s mass on periodic table

For example:

1 mole Carbon = 12.01 grams

1 mol C = ? Atoms C

12.01 grams of Carbon = ? atoms

6.02 x1023 atoms

Reminder: 1 ATOM of C weighs 12.01 amu’s.

What is the molar mass?

Copper (Cu)

63.55g = 1 mol Cu

Oxygen (O2)

16.00g per mol of O…but…

32.00g = 1 mol O2

The mass of the mole, silly!

What is the molar mass?Copper II Oxide (CuO) (What’s the roman numeral mean? Why II?)

63.55g /mol Cu

+ 16.00g /mol O

79.55g /mol CuO You try Ammonium nitrate,

NH4NO3 2 (14.0) g/ mol N 4 ( 1.0) g/ mol H+ 3 (16.0) g/ mol O 80g/mol

Dimensional Analysis

Conversion factors can be used to convert units

12.01 g = 1 mol C

3.85 mol C would have a mass of what?

3.85 mol C (1 mol C)(12.01g C) = 46.2 g C

3.2 mol of malachite,Cu2CO3(OH)2

is how many grams?

1 mol= 221.13 g

3.2 mol

Practice WB pp 53-54

(1 mol malachite)(221.13g malachite) = 708 g Malachite

Mole Ratio’s in Balanced Equations Coefficients represent mole ratios

2CuO2CuO + C --> 2Cu + COCO22

2 mol CuO / 1 mol CO2

How many moles of CuO is needed to produce 8 moles of CO2?

8 mol CO2Note: BOTH units cancel! (1 mol CO2)

(2 mol CuO)

= 16 mol CuO

To Do:

Bring a piece of sugarsugarfulful gum in the wrapper tomorrow.

Balanced

4NH3 + 7O2 --> 4NO2 + 6H2O

How many moles of oxygen are needed to react with 200 moles of ammonia (NH3)

200mol NH3 (7mol O2)(4 mol NH3)

= 350mol O2

How many grams of O2 is that equal to?

350 mol O2

(1 mol O2)(32 g O2) = 11,200 g O2

1 mol = 6.02 x 1023 I AM FU

..1 mole 1 mole NaClNaCl = 6.02 x 10 = 6.02 x 102323 formula units of formula units of NaClNaCl

ons

t oms

o l ecu l e s

o rmu l a

n i t s

•1 mole 1 mole NHNH44++ = 6.02 x 10 = 6.02 x 102323 ions ions NHNH44

++

•1 mole Au = 6.02 x 1023 atoms Au•1 mole CO2 = 6.02 x 1023 molecules CO2

•1 mole equalsmole equals formula mass on periodic tablemass on periodic table

•Mole to mole ratios of different substancesdifferent substances are the coefficients in balanced equationscoefficients in balanced equations

REVIEW

•Coefficients in balanced equations are NOT gram to gram ratios, must first convert to moles to use molar ratio

Practice:Calculate Reactant mass & Product mass

NH3 + O2 --> NO2 + H2O 17g 32g 46g 18g 49g 64gSo what do we need to do?

Balance the equation

4NH3 + 7O2 --> 4NO2 + 6H2O 68 g 224g 184g 108g 292g = 292g

May theMay theMoleMole

be with you !!be with you !!