Chemistry SM-1131Week 7 Lesson 1

Dr. Jesse ReichAssistant Professor of Chemistry

Massachusetts Maritime AcademyFall 2008

Class Today• Polyatomic anions, Molecular Compounds, Acid

Names, Formula Mass • Grams, atoms, mols, avogadro’s number• Take home quiz for Friday

Review• Polyatomic Ions• Ionic Compounds are between metals and

non-metals, AND metals and polyatomic atoms

• Poly=Many• Atomic= Atoms• Polyatomic= many atoms

Polyatomic Anions• Compounds still work basically the same way• 1- Symbols (keep the parenthesis)• 2- Charges• 3- Switcheroo• 4- Reduce

Example• Sodium and Carbonate combine to make a

compound. What’s the formula and charge?• Na & (CO3)

• Na+1 and CO3-2

• Na2(CO3)• Metal First polyatomic ion second• Sodium Carbonate

Example 2• Magnesium and Phosphate come together to

form a compound. Formula and charge?• Mg & (PO4)

• Mg+2 & (PO4)-3

• Mg3(PO4)2

• Metal first polyatomic ion second• Magnesium Phosphate

Example 2 cont.• Mg3(PO4)2• There are 3 Magnesium atoms• There are 2 PO4 groups• Each PO4 group has 1 P and 4 O• So, we have to multiply:• 2x 1P = 2P• 2x 4O = 8O• Total: Mg3P2O8

Example 3• Iron (III) and Nitrate form a compound.

What’s the formula and name?• Fe(III) & (NO3)

• Fe(III)+3 & (NO3)-1

• Fe(III)1(NO3)3

• Iron (III) nitrate• Formula = Fe(III)1N3O9

Example 4• Ammonium and Permanganate form a compound.

Formula and Name?• (NH4) & (MnO4)

• (NH4)+1 & (MnO4)-1

• (NH4)1(MnO4)1

• Ammonium Permanganate• This guy is a rarity because the non-metal thing is the

cation and the metal thing is the anion. Polyatomics can act a little differerntly than metals or non-metals that are just by themselves.

Polyatomics to Memorize

• Table 5.6 page 138• Make note cards. They are all fair game.

Molecular Compounds• Ionic compounds are between metals and

non-metals (or polyatomic ions)• Molecular compounds are between 2 or

more non-metals

Molecular Compounds• Two different naming systems. DON’T

CONFUSE THEM!• This system is just for molecular compounds.• Molecular compounds have 2 or more non-

metals in them

Molecular Nomenclature

• The naming systems for the simple ones works like this:

• 1-Prefix • 2-First element (somewhat alphabetical)• 3-Prefix• 4-Second element• 5-change the ending of the second element to

-ide.

What are the prefixes• MEMORIZE THESE!• Mono-1• Di-2• Tri-3• Tetra-4• Penta-5• Hexa-6• Hepta-7• Octa-8

Example

• Here’s a formula: N2O4. What’s the name?• Di• Nitrogen• Tetra• Oxygen• Oxide• Dinitrogen tetraoxide

Example 2• SF6• Mono (If mono is the very first one you don’t

have to use it).• Sulfur• Hexa• Fluorine• Fluoride• Sulfur Hexafluoride

Example 3

• CO2

• Mono (drop it)• Carbon• Di• Oxygen• Oxide• Carbon Dioxide

Acids• Acids are things that create H+ ions when

dissolved in water. They are typically bitter and sour tasting. Most acids can dissolve metals.

• They are combinations of H+ atoms with anions

Acid Types• Binary Acids• Oxyacids

Binary Acid Names• Binary Acids are a combination of 2 things.

Hydrogen and one other non-metal• Naming them is simple• 1-Hydro• 2-Base name of non-metal• 3-change the ending of the non-metal to –ic• 4-Add the word acid at the end

Binary Acid names• HBr• 1-Hydro• 2-Brom• 3-ic• 4-Acid• Name= Hydrobromic acid

Binary Acid Names• HCl• 1-Hydro• 2-Chlor• 3-ic• 4- Acid• Name= Hydrochloric Acid

Oxyacid Names• Oxy Acids are built around compounds that

have oxygen containing polyatomic anions in them.

What polyatomic anions make sense?

• Phosphate (PO4)

• Phosphite (PO3)

• Chlorate (ClO3)

• Chlorite (ClO2)

• Nitrate (NO3)

• Sulfate (SO4)

• Sulfite (SO3)

Oxyacid naming with-ate

• 1-Name of the polyatomic acid• 2-change the ending to –ic (sometimes needs

a fudge factor)• 3-add the word acid

Oxyacid Naming• Phosphate makes an acid. What is the name and

formula?• 1-Phosphate• 2-turns into Phosphoric• 3- add acid• Name= Phosphoric Acid• 1-H (PO4)

• 2-H+1(PO4)-3

• 3-H3(PO4)1

• Can’t reduce

Naming Oxyacids with -ite polyatomic anions• 1-Write the anion name• 2-Change the ending to –ous (might need a

fudge factor)• 3- add the word acid

Oxyacid Naming with -ite polyatomic anions

• The polyatomic anion sulfite forms an oxyacid. What is the name and formula?

• 1-Sulfite• 2- Change to Sulferous• 3- add Acid• Name= Sulferous Acid• H (SO3)• H+1 (SO3)-2• H2(SO3)1

• Can’t reduce

Molecular Mass• To figure out molecular mass you have to

know the atomic mass.• Let’s start easily• Ne- it exists by itself and doesn’t form

molecules. It’s mass is just the atomic mass of Ne, which is 20.18

Simple Molecule Mass

• The mass of N2 is going to be twice the mass of 1 atom of N

• So, if N has an atomic mass of 14.01, then N2 must have a mass of 2x14.01 or 28.02

Molecular Mass• Ozone has the formula O3, what is it’s

molecular mass• 1 Oxygen has a mass of 16.00• 3x(16.00) has a mass of 48.00 amu

More Complex Masses

• Water has the formula H2O• The molecular mass is going to be from 2H

atoms and 1 O atom, so• 2x(1.0079) + 1x(16.00)= 18.0158amu

Sugar

• C6H12O6

• 6(12.01) + 12(1.0079) + 6(16.00)= ???

New Material• Moles, Atoms, Molecules, grams• IT’S MATH HEAVY TODAY! PAY ATTENTION

YOU SCURVEY DOGS!

Moles• Dozen: 12 somethings• Baker’s Dozen: 13 Somethings• A Score: 20 Somethings • Avogadro’s number: 1 mol= 6.022e23

somethings

See how it works• A dozen atoms = 12 atoms• A baker’s dozen atoms = 13 atoms• A score of atoms = 20 atoms• A mole of atoms = 6.022e23 atoms

Moles• 1 mole of atoms = 6.022e23 atoms• 2 moles of atoms= 2(6.022e23)atoms=

1.2044e24 atoms• 3 moles of atoms = 3(6.022e23)atoms=

1.8066e24

Moles• 1 mole of kittens = 6.022e23 kittens• 2 moles of kittens= 2(6.022e23)kittens=

1.2044e24 kittens• 3 moles of kittens = 3(6.022e23)kittens=

1.8066e24

Moles• It just means a big number.• 602,200,000,000,000,000,000,000,000• But we do this because it converts amu to

grams

Why a 6.022e23• 1 amu = 1.66e-24 grams• So, 1.66e-24gx6.022e23= 0.99652g which is very

similar to 1g.• The point is that if you multiply the mass of

something in amu you can convert amu into a mass in grams

• We don’t weigh anything in amu, but we do in grams so this is useful.

• So, if we multiply the atomic mass of something by 1 mol it turns from amu into grams.

If you have 1 mole of N2 how much would it weigh?• Atomic Mass of N= 14.01 amu• Molecular Mass of N2= 28.02 amu• 6.022e23 atoms of N2 x 28.02 amu x 1.66e-24g =

1 atom 1 amu

Which equals 28.02g. So, 1 mol x molecular mass = # of grams

What do we do with this?

• Chemists generally convert moles into atoms.• Atoms into Moles• Moles into grams• Grams into Moles

Moles into atoms• 1 mole has 6.022e23 atoms in it• 5 moles of Ne x 6.022e23 atoms = 3.011e24 atoms 1 mole

• 24.00 moles of He 6.022e23 atoms = 1.445e25 atoms

1 mole

Atoms into Moles• You have 18.066 e23 atoms of Cu many many

moles of Cu do you have?18.066e23 atoms x 1 mol = 3.0000 mol 6.022e23 atoms

So• Atoms x 1 mole = moles 6.022e23 atoms• Moles x 6.022e23 atoms = atoms 1 mole

Moles to grams• We also convert moles into grams• You can’t weigh a mole, you weigh a gram• Moles x molecular mass in grams = grams 1 mole

Moles to Grams Example 1

• 5 moles of N2 is how many grams?Copy the given5.000 moles x grams = grams 1 molesHow many grams in 1 mole? Use the atomic

mass. N= 14.01amu, so N2= 28.02amu5.000 moles x 28.02 g = 140.1 g 1 mole

Moles to Grams Example 2

• 8 moles of O3 is how many grams?Copy the given8.000 moles x atomic mass in grams = grams 1 molesHow many grams in 1 mole? Use the atomic

mass. O= 16.00 amu, so O3= 48.00amu8.000 moles x 48.00 g = 384.0 g 1 mole

Moles to Grams Example 3

• 10 moles of H2O is how many grams?Copy the given10.0 moles H2O x molecular mass in grams = grams 1 molesHow many grams in 1 mole? Use the atomic

mass. O= 16.00 amu, H = 1.0079 so H2O= 18.0158amu10.0 moles H2O x 18.00158 g = 180.0158 g = 180g 1 mole

Grams to Moles• Grams -> Moles• Xgrams x moles = moles Atomic mass

Grams to Moles example 1

• 2000 g of He into moles• 2000 g x 1 mole He = X moles Atomic Mass• Molecular mass of He 4.00• 2000 g x 1 mole H2O = 500 moles 4g

Grams to Moles example 2

• 450 g of O3 into moles

• 450g x 1 mole O3 = X moles Molecular Mass• Molecular mass of O3 3(16)= 48 amu• 450g x 1 mole O3 = 9.375 moles= 9.4 moles 48g

Grams to Moles example 3

• 270 g of H2O into moles

• 270g x 1 mole H2O = 15 moles Molecular Mass• Molecular mass of H2O 16+1+1= 18

• 270g x 1 mole H2O = 15 moles 18g

If there is time• Convert the following• 15 moles N2 into atoms

• 15 moles of N2 into grams

• 28g of N2 in moles

• 28g of N2 into atoms (2 conversion factors)