Moles And Volume of a Gas

Mass <---> Moles <---> Volume   

• At a specific pressure and temperature one mole of gas occupies the same volume
• At 0'C 101.3 KPa 1 Mole = 22.4L
• This temperature and pressure is called STP
• 22.4L/Mol is the molar volume at STP

Ex. How many liters will 5.0 mol occupy at STP.

5.0Mol * 22.4L 
              --------  = 112 L
               1 Mol 

Ex. At STP a sample of Nitrogen gas contains 15.5. How many liters are there?

15.5 Mol * 22.4L
                 -------- = 347.2 L
                  1 Mol

Ex. STP an Hydrogen gas occupies 12 liters. How many moles of gas must be there?

12L * 1 Mol
         -------- = 0.54 Mol
           22.4L

Molar Mass

Molar Mass - The mass of one mole of a substance. (Mass is in grams)
                      - Measured in g/mole
                      - Mass could be found using the atomic mass on the periodic table

Molar Mass of Compounds
   To find the molar mass of compounds add the mass of all atoms.
  
Element                                 Molar Mass
H20                                      2(1.0) + 16.0 = 18.0 g/mol
NO2                                     14.0 + 2(16.0) = 46.0 g/mol
NaCl                                     23.0 + 35.5 = 50.5 g/mol

*Always remember Significant Digits.

Then there is converting between grams and moles
   We use molar mass as the conversion factor to convert mass and mole.

Example

Find the mass of  0.89mol of CaCl2

0.89mol x     111.1   g              = 98.879g   = 99g                40.1 + 2(35.5) = 111.1
                 ------------
                         1    mol

Determine the number of moles of C5H12 that are in a 362.8g of the compound.

362.8g x         1      mol           = 5.039mol                           5(12.0) + 12(1.0) = 72.0
               --------------
                     72.0    g    

Avogadro's number (how we count atoms)

Atoms and molecules are really really small, so it would take a very very long time to count them.
How do we measure them then?
A man named Amedeo Avogadro proposed that the number of atoms in 12 g's of carbon can be equal to a constant(which is equal to 1 mol of carbon). 
What is a mol? No not a mole!

A mole(mol) is just a unit of measurement for atoms, molecules and formula units, like how a dozen is equal to twelve or how a millennium is 1000.
What is Avogadro's #? 

So how big is a mol? If we used real life a real life example, 1 mol of meters would cross the galaxy over 3000 times.                                                                 

Example of figuring out how many moles is in an element

A sample of  Hydrogen contains 2.2 times 10 to the power of 21 atoms. How many moles of carbon is this?

In order to figure out this problem, we use dimensional analysis. You want to figure how many moles there are and so to do this, you want to cancel out atoms, so you use Avogadro's number!

So you write 2.2 x 10^21 atoms times 6.02 x 10^23 moles/atoms. The atoms cancel each other out and you end up with 1.32 x 10 to the power of 45!

 

 

Second Lab Hydrate Lab

Hydrates are ionic compounds that contain an inorganic salt compound loosely bound to water.
The purpose of this lab was to determine the practical formula of a hydrate.


In this lab we determined the mass of the hydrate without water (anhydrous)


We used:
-Bunsen Burner
-Test tube
-Test tube clamp
-Test tube rack
-Weight scale
-Cobaltous Chloride Hexahydrate


First we filled the test tube with Cobaltous Chloride Hexahydrate then weighed it.
Then we began to use the Bunsen burner while using the clamps to hold the test tube over it.
We noticed the Cobaltous Chloride Hexahydrate turn from the color red to a light blue.
Then we re-weighed the test tube.


The percent of water in Cobaltous Chloride Hexahydrate was 45%.

Chemical Nomenclative

Chemical Formulas 

• Be aware of the difference between ion and compound formulas

Multivalents Ions

• Same elements can form more than one ion
• the top number on the periodic table is more common
• IUPAC uses roman numerals in parenthesis to show the charge
• Classical system uses Latin names if the element and the suffixes ic (Larger charge) and ous (Smaller charge)

* Latin names

1. Ferr - Iron
2. Cupp - Copper
3. Mercur - Mercury 
4. Stann - Tin
5. Aunn - Gold 
6. Plumb - Lead 

Complex Ions

• Complex ions are larger groups of atoms that stay together during a chemical reaction
• Almost all are anions (Negative charge)

 Hydrates

• Some compounds can form lattices that bond to water molecules 
• These crystals contain water inside them which can be released by heating
• To name hydrates

1. Write the name of the chemical formulas
2. Add a prefix indicating the number of water molecules (mono=1, di=2, tri=3)
3. Add the hydrate after prefrix

Naming Acids and Base

• Hydrogen compounds are acid
• Hydrogen appears first in the formula unless it is part of polyatomic group
• If there is OH in the formula it is a base

Electronic Structure

Drawing Electron dot diagrams:
The nucleus is represented by the atomic symbol for individual elements of valence electrons.
Electrons are represented by dots around the symbol.
There are four orbitals each holding a maximum of electrons. Each orbital gets at least 1 electron before they pair up.

Lewis Diagrams for compounds & Ions
To do a lewis diagram for compounds & ions
1) Determine the # of valence electrons for each atom in the molecule
2) Place atoms so that valence electrons are shared to fill each orbital

Hydrogen has an extra one and chlorine needs one.

They form a covalent bond and share electrons.

Double and triple bonds:

Sometimes the only way covalent compounds can fill all their valence electron levels is if they share more than 1 electron.