Chemistry SM-1131
Week 7 Lesson 1
Dr. Jesse Reich
Assistant Professor of Chemistry
Massachusetts Maritime Academy
Fall 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 nonmetals 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 given
5.000 moles x grams = grams
1 moles
How many grams in 1 mole? Use the atomic
mass. N= 14.01amu, so N2= 28.02amu
5.000 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 given
8.000 moles x atomic mass in grams = grams
1 moles
How many grams in 1 mole? Use the atomic
mass. O= 16.00 amu, so O3= 48.00amu
8.000 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 given
10.0 moles H2O x molecular mass in grams = grams
1 moles
How many grams in 1 mole? Use the atomic
mass. O= 16.00 amu, H = 1.0079
so H2O= 18.0158amu
10.0 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)