CHEMICAL QUANTITIES

Measuring Matter Count Weigh Volume Each of these measurements is related to a single quantity called the “mole”

The Mole A mole is a convenient standard quantity used to count representative particles. WHY? because …. atoms and molecules are so tiny, chemists use this counting unit called the mole. it represents 6.02 x molecules or atoms or particles

Representative particles: the type of particle that make up a substance substancerepresentative particles elements  atoms Molecular compounds  molecules Ionic compounds  formula units

Just as a dozen is always 12, a mole is always 6.02 x This is called Avogadro’s number because Amedeo Avogadro came up with the idea!! Who is he, you ask?.....

Amedeo Avogadro Was a lawyer and scientist (physics) In 1811 proposed that equal volumes of all gases contain the same number of molecules How many? Good question!......

The number of molecules in 1 mole of gas is known to be x He was right and so we now apply this to all molecules (not just gases).

The mole is so important to chemistry that we actually have National Mole Day. It is every October 23 from 6:02 in the morning until 6:02 in the evening.

HOW DO YOU CELEBRATE MOLE DAY?????

Better ideas……….!

Just imagine…. If you had a mole of dollars ($6.022 x ) and you spent $1 billion every second of every minute of every hour of every day for 70 years…. You would have spent less than 1% of your money! WOW!

Examples 1 mole of carbon = x C atoms. 1 mole of water = x H 2 O molecules. 1 mole of sodium chloride = x NaCl formula units. 1 mole of glucose = x C 6 H 12 O 6 molecules. Pretty simple, eh?

Converting from moles to Representative particles multiply by x MOLES REPRESENTATIVE divide by x PARTICLE

You try it…. How many moles of magnesium are 3.01x atoms of Mg? Answer: 3.01x atoms 6.02 x atoms/mol = x = 5.00 x mol Mg

Practice! Do problems #5 - 8 on page 51-52

If you want the number of atoms in a mole of a compound… you must know how many atoms are in the compound Ex: how many atoms are in 1 mole of CO 2 ? 1 mol X x atoms/mol X 3 atoms = x atoms = 1.81 x atoms

If you want the number of ions in a mole of a compound… you must know how many ions are in the compound Ex: how many F - ions are in 1.46 mole of AlF3? 1.46 mol X x formula units/mol X 3 F - ions = x F - ions = F - ions

Do problems # On page 52

Converting from representative particles reverses the process Atoms, molecules, formula units are divided by Avogadro’s number to get the number of moles!

How many moles are present in a sample of 5.83 x molecules of CO 2 ? 5.83 x molecules of CO x molecules /mol = x 10 1 mol of CO mol of CO 2

Turn to page 53 Answer questions #12-15

New Stuff……

Moles Representative Particles Multiply by 6.02x10 23 Divide by 6.02x10 23 Mass Divide by molar mass Multiply by molar mass

Molar Mass Molar mass is the mass in grams of one mole of any element or compound. The units for molar mass are g/mol It can refer to atoms,molecules or formula units. Huh?

Molar Mass Gram atomic mass…… used for elements Gram molecular mass…. used for molecules Gram formula mass..... used for ionic compounds All of these can be referred to as gram formula mass or molar mass …………..…what?!

Gram Atomic Mass (gam) is the mass in grams of an atom = 1gam Numerically it is equal to its atomic mass (you know…on the periodic table!) Ex: 1mol S = 32.1g = 1gam S 1mol Hg = 200.6g = 1gam Hg 1mol Fe = 55.8g = 1gam Fe

Example: Molar mass of carbon (aka gram atomic mass) is the mass of one mole of carbon, which would be g/mol (refer to atomic mass of C on periodic table). What would be the molar mass of He? What would be the molar mass of Ba?

Gram Molecular Mass (gmm) is the mass in grams of the atoms which make up the molecule Ex: 1mol SO 3 = 32.0g + 3(16.0g) = 80.1g = 1gmm 1mol C 6 H 4 Cl 2 = 6(12.0g) + 4(1.0g) + 2(35.5g) = 147.9g = 1gmm

Molar mass of water (aka gram molecular mass) would be the mass of one mole of water………. which we find by adding up the atomic masses of each element in the molecule. Molar mass (H 2 O) = 2 x 1.01 = x 16.0 = g/mol What is the molar mass of sulfuric acid? H 2 SO 4 = (2 x 1.01) + 1(32.0) + 4(16.0) = 50.01g/mol

Gram Formula Mass (gfm) is the mass in grams of the ions which make up the ionic compound Examples: 1mol potassium iodide (KI) 39.1g g = 166.0g = 1gfm KI 1mol ammonium carbonate (NH 4 ) 2 CO 3 2(14.0g) + 8(1.0g) g + 3(16.0g) = 96.0g = 1gfm (NH 4 ) 2 CO 3

All solids, liquids and gases can be converted from mass to moles and vice versa. From mass to moles: divide by molar mass From moles to mass: multiply by molar mass multiply by molar mass MOLESMASS divide by molar mass

EXAMPLE: What is the mass of 4.2 mol of silver nitrate? ANSWER: Mass = 4.2 mol x g/mol = 713.5g From moles to mass…… Multiply by molar mass Molar mass = AgNO 3 = (107.87) + (14.01) + 3(16.00) = g/mol

Rasputin! Ever hear of him….?

If his murderers had calculated the correct quantity of potassium cyanide, they could have killed him with much less effort….

HCl + KCN  HCN + KCl hydrochloric acidpotassium cyanide hydrocyanic acid potassiun chloride However, they would have had to know about his unique medical condition first……. HCl + KCN  KCN + HCl hydrochloric acidpotassium cyanide potassium cyanide hydrochloric acid KCN  KCN potassium cyanide

See…….. chemistry is useful in everyday life!