MultiStep Conversions

MASS    <-------->      MOLES  <-------->    VOLUME(@STP)
               molar mass          |         mass volume
                                          |
                                          |
                                MOLECULES   ( Avogardo's number)
                                          |
                                          |
                                    ATOMS     ( subscripts)

 Remember : when you are converting, you must always go back to moles first!
                          ** with the exception of molecules to atoms or atoms to molecules

EXAMPLES:

- 11.5g of H2 gas are placed in a balloon at STP. Determine the volume of the balloon.

(there is 2 ways to do this)

1.)   step 1 : 11.5g x 1mol    = 5.75 mol
                    2.0g 
   
        step 2 : 5.75 mol x 22.4 L    = 128.8 = 129 L    (*dont forget your significant digits)
                                      1 mol
                                     
                                       OR
2.)   11.5g x 1 mol      x   22.4 L   = 129 L
                    22.4 L         1 mol



REMEMBER TO STUDY FOR YOUR MIDTERM !!!

Nicole H

The Day Mr.Doktor Was Away

We had a sub for this class, and Mr.Doktor left us some with a worksheet and some homework. Here is a few examples and an overview of what was assigned:

Moles to Atoms/Molecoles 
Molecules/Atoms to Moles


EX. How many atoms are there in 1.5mol or Iron?

1.5 mol x 6.02E32 atoms = 9.03E23 atoms
                        1mol

How many moles of magnesium bromide (MgBr2) contain 5.28E24 formula units?

5.38E24 FU x 6.02E23 FU = 8.94 mols
                          1 mol


Determine the number of atoms that are in 0.58 mol of Se.

0.58 mol x 6.02E23 = 3.5E23 atoms
                     1 mol

Janine R

Molar Volume Lab

In the lab we did last class, it helped us work towards what we're learning in chemistry right now which is converting L/mol.

During this lab, we filled a sink full of water up to the point where we could fully submerge a gradulated cylinder. We made sure that there were no air bubbles within the cylinder with water in it. Before putting the lighter in the water, we weighed it. While keeping the open end in the water and the bottom sticking out at an angle, we took the lighter and put it under the water, under the opening of the gradulated cylinder and held the lighter button so that only butane would come out. Until the cylinder was filled up to 100mL of butane, we took out the lighter and shook it, and then put it in the warm drying area so that we could weigh the lighter afterwards. There was a bit of a difference in the weight, but there shouldn't be much of a difference in the weight.

The purpose of this lab was to experimentally determine the molar volume of a gas.

Sofia Nguyen

Moles to Volume Conversion

- At specific pressure and temperature one mole of any gas occupies the same volume.
- At 0 degrees C and 101.3 kPA
1 mole = 22.4 L
- This temperature is called STP

-- 22.4 L/mol is the molar volume as STP

Examples:

- How many litres will 3.5 Cl(g) occupy at STP?

3.5 mol x  22.4 L = 78.4 L
                1 mol
( because there is only 2 significant digits the answer becomes 78 L )

- A certain gas is found to occupy 12.3 L at STP. How many moles of gas is there?

12.3 L x  1 mol    =   0.549 mol
               22.4 L

- At STP an unknown gas is found to occupy 150mL. How many moles of gas must be there?
    1L = 1000mL
150 mL x   1 mol     = 6.6964 mol
                 22.4 mL  
6.6964 mL             
  1000                          = 0.0670 mol

*** remember you must convert your mL to L. Doesn't matter if you do it first or last!
      
Nicole H

Molar Conversion

Converting Between Moles and Mass
- to convert between moles and mass we use molar mass as the conversion factors
- BE SURE TO CANCEL THE APPROPRIATE UNITS

Examples:

How many grams are there in 2.5 mole of P4  (  F2 : 19.0 x 2 = 38)

Step 1: 2.5 mol                         g   =         g
                                             mol
Step 2: 2.5mol          38.0          g  =    95 g  
                                  1         mol

Remember!!!!!
            -significant digits
            -0 is NEVER a significant digit
            - balance chemical equations first

A compound is made of phosphorous and chlorine. It is found to contain 0.200 mol and has a mass of 27.5
- determine molar mass of the compound
- suggest possible formula

27.5 g         = 137.5 g/mol
0.200 mol 

PxCly:       X              Y       MOLAR MASS
                  1              2                  102
                  2              1                 97.5
                  2              2                 133
                  1              3                 137.5                  
Phosphorous and chlorine = PCl3

Nicole H

Molar Mass

molar mass - the mass (g) of 1 mole of a substance
-the molar mass is the atomic mass
-molar mass is measured in g/mol

Molar Mass of Compounds
-to determine the molar mass of a compound, you add the mass of all the atoms together
EX.
C12H22O11 --> 12.0(12)+1.0(22)+16(11) = 342.30g/mol
KCl --> 19+17 = 36g/mol
NaBr4 --> 23.0 + 79.9(4) = 342.6
(NH4)2S --> (( 14+1 (4) )) x2 + 32.1 = 54.1g/mol

Janine Roldan

Chapter 2 Test

A review of chapter 2:

Atomic theories

JJ Thomson - raisin bun theory
                    - he beleived there was a solid, postive sphere with negative
                       particles embedded



Bohr and Lewis Diagrams



Quantum Mechanics


S orbital - each orbital holds 2 electrons
P orbital - 3 suborbitals: contain 2 electrons each
D orbital - 5 suborbitals: contain 2 electrons each
F orbital - 7 suborbitals: contain 2 electrons each

Naming Compunds



IUPAC= using roman numerals in pararanthesis
Classical System= use latin names of the element
ex. Aunn: gold
      Ferr: iron
- when using the classical system the larger charge you use ic and the smaller charge ous

Nicole H

Hydrate Lab (November 4)

The purpose of this experiment was to determine the empirical formula of hydrate. In this lab we determined the anhydrous(w/out water) mass of the hydrate. We also compared this with the actual mass of water that should have been present.


Janine Roldan

Molecular Compounds

Molecular Compounds

• molecules are diatomic 
• 2 of the same elements: H2, N2, O2, F2, Cl2, Br2, I2
• 2 molecules are polyatomic: S8, P4

Naming Molecular Compounds

• use the name of the first element
• second element ends in -ide
• 1st atom usually doesn't have a prefix EX. CO2 -> carbon dioxide
• hydrogen doesnt have a prefix EX. H2S -> hydrogen sulfide

More examples:

HBr -> hydrogen bromide

KI -> potassium iodide

H20 -> dihydrogen oxide

Naming Acids and Bases

• hydrogen compounds are acids

EX. 

HCl -> hydrochloric acid

H2SO4 -> sulfuric acid

Naming Bases

• cation and OH

EX.

Na(OH) -> sodium hydroxide

Ba(OH)2 -> barium hydroxide

Sofia Nguyen

Naming Compounds

Chemical Nomenclature

Todays most common system is IUPAC for most chemical reactions like:
- ions
- binary ionic
- polyatomic ions
- hydrates
-molecular compounds
- acids/ bases

Chemical Formulas
- be aware of the difference between and ion and a compound.
ion= charge
compound= no charge



Note: -the top charge on a multivalent is the most commonly used
           -IUPAC use roman numerals in parenthesis
           - classical systems use latin names of the elements

suffixes ic is the larger charge and ous is for the smaller charge
ex. Fe0 - ferrous oxide

Classical names are a bit different for some elements like:
Ferr : iron
Cupp: copper
Stann: tin
Plumb: lead

Hydrates
some compounds can form lattices that bond to water molecules by hydrates

-watch this video to learn how to make/ name hydrates
http://www.youtube.com/watch?v=HM2C5FEvR0g

Nicole Haughian

How to Draw Electron Dot Diagrams

Electron Structure: Electron Dot Diagrams

Drawing Electron Dot Diagrams


follow this link --> http://www.youtube.com/watch?v=y6QZRBIO0-o (:


Lewis Diagrams for Compounds and Ions

·                     in covalent compunds electrons are shared

·                     one atom gives up an electron to the other, forming positive and negative ions

1.                   First determine the number of valence electrons for each atom in the molecule

2.                  Then, place atoms so that valence electrons are shared to fill each orbital

EX.

carbon tetrafluoride

Double and Triple Bonds

EX.

oxygen: it's outer shell contains 6 electrons so it needs another 2 electrons in this case shared to get a stable configuration

Ionic Compounds

·                     the formation of an ionic bond is the result of the transfer of one or more electrons from a metal to a non-metal

·                      draw [brackets] around the metal and non-metal

·                     for metals: Energy + Metal Atom ---> Metal (+) ion + e-

·                     for non-metals: Non-metal Atom + e- --- Non-metal (-) ion + energy

EX.

JANINE ROLDAN

Trends on the Periodic Table.

 There are some things on the periodic table that you wouldn't know about just by looking at it, but by actually studying and researching about it.

Did you know that elements close to each other on the periodic table display similar characteristics? 

TRENDS

There are 7 important periodic trends that you'd have to know;

1. Reactivity

2. Ion Charge

3. Melting Point

4. Atomic Radius

5. Ionization Energy

6. Electronegativity

7. *Density 

You actually don't need to know much about density.

REACTIVITY

• Metals and non-metals show different trends
• The Most reactive metal is Francium; the most reactive non-metal is fluorine.

ION CHARGE

• Elements that that contain ion charges depend on their group (column)

MELTING POINT

• Elements in the center of the table have the highest melting point
• Noble gases have the lowest melting points
• starting from the left and moving right, melting points increase until the middle of the table

ATOMIC RADIUS

• Radius decreases up the right 
• Helium has the smallest atomic radius 
• francium has the largest atomic radius

IONIZATION ENERGY

• Ionization energy is the energy needed to completely remove an electron from an atom
• it increases going up and to the right of the periodic table
• all noble gases have high ionization energy
• Helium has the highest ionization energy and Francium has the lowest ionization energy

ELECTRONEGATIVETY

• Electronegativity refers to how much atoms want to gain electrons
• some trend such as ionization energy

IF YOU WANT TO LEARN MORE PLEASE REFER TO THE FOLLOWING LINKS! :)

http://chemistry.about.com/od/periodictableelements/a/periodictrends.htm

http://dl.clackamas.cc.or.us/ch104-06/periodic.htm

A SONG THAT COULD HELP YOU REMEMBER THEM

http://www.youtube.com/watch?v=dHcD_But7dU

http://www.youtube.com/watch?v=dHcD_But7dU

SOFIA NGUYEN