The Mole Chapter11

I. The mole and Avogadro’s number

What is a mole? A machine that bores through hard surfaces, used especially for tunneling through rock. A spy who operates from within an organization, especially a double agent operating against his or her own government from within its intelligence establishment.

An animal

A birth mark

In Chemistry From the atomic structure unit we learned that 1 atom of any element is equal to the atomic mass on the periodic table. The units for atomic mass is amu (atomic mass unit)

Example: 1 atom of hydrogen = amu of hydrogen

However, in a laboratory it would be difficult to work with atoms, since they are so small Instead we use the same atomic masses on the periodic table, but use the units of grams (per mole)

Example: 1 mole of hydrogen = grams of hydrogen

The value of the mole was experimentally defined by the number of carbon atoms in grams of carbon. There are 6.02 x atoms of carbon in grams of carbon x is referred to as Avogadro’s number. It represents a specific amount of something.

It’s really just a word to represent a number…

Just like: a couple of cookies = __2__ cookies a dozen doughnuts = _12_ doughnuts a gross of geese = __144___ geese;

a mole of mints = 6.02 x mints a mole of basketballs = 6.02 x basketballs a mole of marshmallows = 6.02 x marshmallows

"mole" represents the number x or

Although a mole can be used to describe any type of object, it is usually limited to subatomic particles. a mole of atoms = 6.02 x atoms a mole of molecules = 6.02 x molecules a mole of formula units = 6.02 x formula units

A mole of anything can be difficult to imagine. A mole of marbles is enough to cover the earth to a depth of 50 miles! Whoa, that’s a lot of marbles.

A mole of atoms = 6.02 x atoms A mole of molecules = 6.02 x molecules A mole of formula units = 6.02 x formula units Although a mole can be used to describe any type of object, it is usually limited to subatomic particles.

In your box… 1 mole = 6.02 X atoms, molecules, or formula units

Three ways of representing amounts 12 large eggs 1 dozen eggs 24 ounces of eggs 6.02 X Iron atoms 1 mole of iron atoms grams of iron

Fun Facts It is often referred to as Avogadro's number (in honor of Amedeo Avogadro) “Mole” is derived from the Latin word moles, which means “a mass” “Molecule” is the diminutive form of this word that means “a small mass”

Mole day is generally celebrated on October AT 6:02AM get it?

To compare…. A dozen of eggs will fit in an egg carton A mole of eggs will fill all the oceans on the earth more than 30 million times over It would take 10 billion chickens laying 10 eggs per day more than 10 billion years to lay a mole of eggs

Why use such a big number? We use moles when it comes to atoms and molecules… take a guess? Because atoms are so small

B. Calculating with Avogadro’s Number Remember, Avogadro’s number is an equality and you can make 2 conversion factors out of it. Use dimensional analysis to determine the information you are seeking.

The two conversion factors 1 mol___ 6.02 x * 1 mole and * = atoms, molecules, or formula un its

EX 1: Determine the moles of magnesium there are in 1.23 x atoms of magnesium 1.23 x atoms Mg 1 mole Mg 6.02 x atoms Mg = 2.04mol Mg 1 G: 1.23 x atoms Mg W: moles Mg R: 1 mole Mg = 6.02 x atoms Mg

EX 2: Determine the number of atoms in 8.93 moles of argon moles Ar 1 mole Ar 6.02 x atoms Ar = 5.38 x Atom Ar 1

Ex 3: Determine the number of water molecules in 11.2 moles of water moles H 2 O 6.02 x molecules H 2 O = 6.74 x moles H 2 O molecules H 2 O 1

Practice Box

Practice =3.37 x Atoms Pu =19.9Moles of Phosphorus =87.0Moles CCl 4

1. Determine the number of atoms in mol of plutonium mol Pu 1 mole Pu 6.02 x atoms Pu = 3.37 x Atoms Pu 1

2. How many moles are in 1.20 x atoms of phosphorus? 1.20 x atoms P 1 mole P 6.02 x atoms P =19.9Moles of Phosphorus 1

3. How many moles are in 5.24 x molecules of CCl 4 ? 5.24 x molec. CCl 4 1 mole CCl x molec. CCl 4 =87.0Moles CCl 4 1

C. Molar Mass

1. Definition molar mass is the mass (in grams) of 1 mole of any element or compound units for molar mass: g/mol Example: Hydrogen’s molar mass is g/mol

the molar mass of any element equals the average atomic mass on the periodic table in grams

Use your periodic table 1 mol He = grams He 1 mol Ca = grams Ca Other representation for Helium 1 mol He= grams He grams1 mol He

(use a periodic table) the molar mass of iron is g/mol g = 1 mole clean fraction 55.85g Fe 1 mol Fe

the molar mass of gold is g/mol g Au = 1 mol Au clean fraction g Au 1 mol Au

anytime you want to convert from mass (grams) to moles or moles to mass (grams), use molar mass! Tip: if you see mass (or grams) use your periodic table

B. Calculating with Molar Mass

B. Calculating with molar mass EX 1: Determine the mass of 3.50 mol of copper mol Cu63.546g Cu 1 mol Cu = 222 g Cu From the p.t  Copper: g Cu = 1 mol Cu 1

Ex. 2 Determine the number of moles in 11.9 kg of aluminum kg Al1000g Al 1 kg Al = mol Al g Al From the p.t  Aluminum: g Al = 1 mol Al mol Al 1

Practice Box

1. Determine the number of moles in 150 g of sulfur 150g S1 mol S g S = 4.68 From the p.t  Sulfur: g S = 1 mol S mol S 1

2. Determine the mass of 8.95 mol of Li 8.95 mol Li6.941 g Li 1 mol Li = 62.1 From the p.t  Lithium: 6.941g Li = 1 mol Li g Li 1

3. Determine the mass, in kg, of 12.4 mol of Na mol Na22.990g Na 1 mol Na = From the p.t  Sodium: g Na = 1 mol Na 1 kg 1000g kg Na 1

C. Mixed Problems

Tips for solving mole problems 1.If you see “atoms,” “molecules,” or “formula units” mentioned in the problem, write 1 mole X = 6.02 X atoms, molecules, formula units X. X = element or compound

Tips for solving mole problems 2. If you see mass involved in the problem, write 1 mol X = (see periodic table) g X X = element

Mole Road Map

Ex 1. Determine the mass of 4.56 x atoms of silver x atoms Ag g Ag1 mol Ag = 817 From the p.t  Silver: g Ag = 1 mol Ag 1 mol Ag Start end x atoms Ag 1 2 g Ag 1

Ex. 2 Determine the number of atoms in 100 g of aluminum 1 mol Al26.982g Al 100 g Al = 2.23 x From the p.t  aluminum: g Al = 1 mol Al 1 mol Al Startend x atoms Al 12 Atoms Al 1

Practice 1. Determine the number of atoms in 0.46 g of copper. 2. Determine the mass (in kg) of 5.98 x atoms of potassium. 3. Which has more atoms, g of aluminum or g of helium?

1. Determine the number of atoms in 0.46 g of copper. 1 mol Cu g Cu 0.46g Cu = 4.36 x mol Cu Startend x atoms Cu 12 Atoms Cu 1

2. Determine the mass (in kg) of 5.98 x atoms of K x atoms K39.098g K1 mol K = mol K Start end x atoms K 1 2 kg K g K 1 kg K

3. Which has more atoms, g of aluminum or g of helium? 1 mol Al g Al = 6.02 x mol Al Startend x atoms Al Atoms Al 1 1 mol He4.003 g He = 6.02 x mol He6.02 x atoms He Atoms He 1

…I don’t get atoms

A closer look If 4 grams of helium is equal to one mole of helium atoms and 12 grams of carbon is equal to one mole of carbon atoms How can we explain 1 mole = 6.02 X x atoms?

1 mole He 1 mole C g/mol g/mol 6.02 X atoms He 6.02 X atoms C

Conclusion Helium atoms are smaller than carbon atoms

Don’t forget what you learned before What does a mass number of 4 represent? Answer: protons + neutrons

Mole and Weight Relationships of Water and its Parts 2 moles +1 mole=1 mole H O H 2 O 2 * 1.01 g g = g

2 moles + 1 mole = 1 mole HO H 2 O 2 * 1.01 g g = g