Polar and Non-Polar Solvents Lab

Objective of this lab: to determine if Glycerin is Polar or Non-Polar

We set up 6 clean, dry test tubes and divided them into 3 sets. 3 test tubes were half filled with water and the other 3 were filled with paint thinner. The first 3 tubes with water, we added table salt, sugar and iodine to each one. All dissolved in each of the solvents. We then added the same 3 substances in each of the test tubes filled with paint thinner. Non of the substances dissolved in the paint thinner. The iodine turned the paint thinner a magenta colour. At the end of the lab we combined water, glycerin and the paint thinner into one tube. It didnt dissolve and the glycerin and paint thinner stayed at the top, creating a jelly look. (like the picture below)

                                       (water, paint thinner and glycerin combined in one test tube)



Janine R

Intramolecular Bonds

Intramolecular: bonds that exist within molecules
     -ionic and covalent
Intermolecular: bonds that exist between molecules
     - stronger the intermolecular nonds the higher boiling point or melting point
     - 2 types : Vander waals and Hydrogen bonds


Vander Waal Bonds

• based on electron distribution
• two categories:   1. Dipole 2. Bonas
• if a molecule is polar the positive end of one molecule will be attracted to the negative end of another molecule

LDF London Dispersion Focus

• is present in all molecules
• -creates weakest bond
• - if a substance is nonpolar dipole the focus doesnt exist
• electrons are free to move around and wil randomly be grouped on one side of the molecule
• this creates a temporarily dipole and can cause a weak bond to form
• the more electrons in the molecule the stronger the LDF can be

Hydrogen Bonding

• if Hydrogen is bonded to certain elements (F, O , or N) the bond is highly polar
• thsi forms a very strong intermolecular bond

Nicole H

Polar Molecules

- polar molecules have an overall charge seperation
- unsymmetrical molecules are usually polar
molecule dipoles: are resulted of unequal sharing of electrons in a moleculE

Predicting Polarity

- If a molecule s symmetrical the pull of electrons are usually balanced
- molecules can be un-symetrical in 2 ways:
1. different atoms
2. different number of atoms

EXAMPLE:
Molecule                  Diagram                                              Polarity

CO2     Non polar (because it is symmetrical)

Nicole H

Types of Bonds

There are three main types of bonds:
1. IONIC (metal - non metal)
      - electrons are transferred from metal to non-metal
2. COVALENT (non-metal - metal)
      - electrons are shared between non metals
3. METALLIC (metal)
      - holds pure metals together by electrostatic attraction

Electronegativity(en)
- en is a measure of an atoms attraction for electrons in a bond
Flourine = 4.0
- atoms with greater en attract electrons more

polar covalent: bonds form from an un-equal sharing of electrons
non-plolar covalent: bonds form from equal sharing

BONDS:
- types of bonds formed can be predicted by looking at the difference in electronegativity of the elements
en > 1.7 = ionic bond
en< 1.7 = polar covalent bonds
en = 0   = non-polar covalent

for examples of electronegativity and bonding please watch the link below :)
http://www.youtube.com/watch?v=Kj3o0XvhVqQ

Nicole H

Ion Concentrations

• when ionic compounds are dissolved in water they contain cation and anion seperate from each other.
• this process is called DISSOCIATION
• Dissociation: is the process in which this happens

Dissociation
ionic compunds are made up of two parts:
-cation - positively charged particles
- anion - negatively charged particles

• when writing dissociation equations the atoms and charges must balance

                ex : Fe(OH)2 ----> Fe 2+ + 2 OH -

EXAMPLE :

Determine [Na+] and [PO4   3-] in a 1.5 M solution of Na3PO4

Na3PO4 ---> 3 Na +    +        PO4 3-

1.5 M  x   3     =  4.5 M = [Na+]
                1

Nicole H

Dilution Lab

We did a lab where we had to figure out which solution contained 0.05 M.  Mr. Doktor did not help us, he only gave hints. Also, we could only use the supplies given at our lab stations



Nicole H

Dilutions

Dilutions - when 2 solutions are mixed the concentration changes

                - the process of decreasing the concentration by adding a solvent(usually water)

                - the amount of solute does not change, only the volume

                - because concentration is mol/L we use the following equations: 

                                       C=n/v and n=Cv  so that    C1V1=C2V2

*always remember to convert mL into L

EX.

How much water must be added to 10.0mL of 10.0M Na2SO4 to give a solution with a concentration of 0.50M?

V1=100mL-->.10L               C1V1=C2V2

C1=0.10M                            

C2=400mL                           C1V1 = V2    ---->  (10.0)(10) = 200mL         changeV=200-10=190mL

                                               C2                             (0.50)

EX.

If a 75.0mL sample of 0.500M KCl is added to 100mL of 0.250M KCl what will the resulting solutions concentrations be?

0.075L x 0.500M = 0. 0375mol               

                   L

0.100L x 0.250M = 0.025mol

                   L

Then add both mols together,

0.0375+0.025= 0.0625mol

After divide the mols by adding both amounts of litres together,

0.0625M = 0.357M

0.175L

Janine R