The Mole Chapter11

I. Atoms, Molecules, and Formula units

The terms atom, molecule, and formula units can be used to represent very similar things.

Atoms The term atoms is used to describe units of uncombined elements from the periodic table. Examples: O, U, Zr, and Ag are all atoms (no subscripts) O

Metals & Non-Metals

Molecules The term molecule is used to describe a molecular compound. This is any compound that contains only non-metals in its formula. Non-metals are found on the right side of the staircase on the periodic table, and also includes Hydrogen. Examples: S 8, N 2 O 2, O 3, and CO 2 are all molecules (all non-metals, more than one atom in the formula) OO C

Formula Units The term formula units are used to describe any unit of an ionic compound, which is any compound that contains a metal in its formula. Metals can be found on the left side of the staircase on a periodic table. Ex. CaO, NaI, and AgNO 3 are all formula units (metal in the formula, more than one atom in the formula) O Ca

The term formula units is long, so we’ll call it FUN. We could abbreviate with just the first letter of each word, but that can easily be misinterpreted as something else… yikes, we don’t want that do we?

Remember, a compound, molecular or ionic, is made up of at least 2 atoms from the periodic table.

Atom, Molecule or FUN? 1)H 2 O 2)Mg 3)NaNO 3 4)Cl 2 5)Ne 6)SC 7)KCl molecule atom Formula Unit molecule atom Molecule Formula Unit

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

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.

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

Atom, Molecule, & FUN Molecule = Compound with only Non-Metals (mc or molec) Formula Unit (FUN) = Compound with a Metal Atom = single PT element *don’t abbreviate molecule as mol or mole

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: W: R: 1.23 x atoms Mg Moles Mg 1 mole Mg = 6.02 x atoms Mg

When you see atoms, molecules, or FUN in a problem your relationship is: 1 mol __ = 6.02 x atom, mc, or fun __

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 G: W: R: 8.93 moles Ar atoms Ar 1 mole Ar = 6.02 x atoms Ar

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 G: W: R: 11.2 moles H 2 O Molecules H 2 O 1 mole H 2 O = 6.02 x mc H 2 O

More Practice

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 G: mol Pu W: atoms Pu R: 1 mole Pu = 6.02 x atoms Pu

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 G: 1.20 x atoms P W: moles P R: 1 mole P = 6.02 x atoms P

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 G: 5.24 x atoms CCl 4 W: mc CCl 4 R: 1 mole CCl 4 = 6.02 x mc CCl 4

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

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 1 G: W: R: 3.50 moles Cu Mass Cu (g) 1 mole Cu = g Cu

When you see atoms, molecules, or FUN in a problem your relationship is: 1 mol __ = 6.02 x atom, mc, or fun __ When you see mass in a problem your relationship is: 1 mol __ = (molar mass) g ___

Ex. 2 Determine the number of moles in 11.9 kg of aluminum kg Al1000g Al 1 kg Al = mol Al g Al mol Al 1 G: 11.9 kg Al W: mol Al R: 1 mole Al = g Al 1 kg = 1000 g G: W: R: 11.9 kg Al Moles Al 1 mole Al = g Al 1 kg = 1000 g

More Practice

1. Determine the number of moles in 150 g of sulfur 150g S1 mol S g S = 4.68 mol S 1 G: 150 g S W: mol S R: 1 mole S = g S

2. Determine the mass of 8.95 mol of Li 8.95 mol Li6.941 g Li 1 mol Li = 62.1g Li 1 G: 8.95 mol Li W: mass (g) R: 1 mole Li = g Li

3. Determine the mass, in kg, of 12.4 mol of Na mol Na22.990g Na 1 mol Na = kg 1000g kg Na 1 G: 12.4 mol Na W: mass (kg) R: 1 mole Na = g Na 1 kg = 1000 g

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

Ex 1. Determine the mass of 4.56 x atoms of silver x atoms Ag g Ag1 mol Ag = mol Ag 6.02 x atoms Ag g Ag 1 G: 4.56 x atoms Ag W: mass (g) R: 1 mole Ag = g Ag 1 mol Ag = 6.02 x atoms Ag

Ex. 2 Determine the number of atoms in 100 g of aluminum 1 mol Al26.982g Al 100 g Al = 2.23 x mol Al6.02 x atoms Al Atoms Al 1 G: 100 g Al W: atoms R: 1 mole Al = g Al 1 mol Al = 6.02 x atoms Al

More 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 Cu6.02 x atoms Cu Atoms Cu 1 G: W: R: 0.46 g Cu Atoms Cu 1 mole Cu = 6.02 x atoms Cu

2. Determine the mass (in kg) of 5.98 x atoms of K x atoms K39.098g K1 mol K = mol K 6.02 x atoms K kg K g K 1 kg K G: W: R: 5.98 x atoms K kg K 1 mole K = 6.02 x atoms K 1 kg K = 1000 g K

3. Which has more atoms, g of aluminum or g of helium? 1 mol Al g Al = 6.02 x mol Al6.02 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