LAB: Iron and and Copper Chloride

Problem: What is the ratio of moles of Copper formed to moles of Iron reacted in the chemical reaction described below?

To find the answer to this question our group placed an Iron nail in a solution of Cupric Chloride after measuring the filter paper and mass of the nail. We observed an immediate change in the color of the nail; it turned a rusty red. We learned that the iron was dissolving. These dissolved iron particles will combine to form Ferric Chloride. After, we removed the nail form the solution and dried it then we transfered the solution in to a separate beaker using filter paper. We measured the mass of the nail. It took a long time for the solution to filter. We determined the mass of Iron consumed  by comparing the mass of the nail before and after the reaction. After the solution had filtered we transferred the Ferric Chloride and the filter paper to dry in the drying oven. We have yet to measure its mass then we can determine the mass mass of the Ferric Chloride formed.

Group: Jennifer, Jomar, Paulette

Density and Moles

Density
-Density is a measure of mass per volume d = m
                                                                      V
-measured in g/L or g/mL

Example
-Water has a density of 1.0g/mL. Determine the mass of 11.5mL of water
-How many moles are in 11.5mL of water?

1.0g/mL x 11.5mL = 11.5g
11.5g x 1 mol = 0.64 mol
             18 g

Density of Gases

-The density of gases varies with temperature

-At STP we can find density by:  MM              molar mass               

                                               22.4L/mol        molar volume

Example
-Calculate the density of 02 STP

32.0g/mol = 1.43g/L
22.4L/mol

-An unknown diatomic gas has a density of 1.696g/mol STP
 -Find its molar mass
 -What is the chemical formula

1.696g/L x 22.4L/ 1 mol = 37.99g/mol = 38g/mol
                                                                  2
                                                            = 19g/mol
Chemical formula : F2

Mass to Volume Conversion

- At a specific pressure and temperature one mole of any gas occupies the same volume.

- At 0 degrees Celsius and 101.3 kilo Pascals 1 mol = 22.4 L

- This temperature and pressure is called STP

- 22.4 L/ mol is the molar volume at STP

Example:

How many litres will 2.5 mol of hydrogen gas occupy at STP

1) 2.5 mol hydrogen gas = 22.4 L/ 1 mol = 556 L

litres to mols

2) 11.6 L = 1 mol/ 22.4 L = 0.518 mol

Example:

At STP a sample of oxygen gas contains 11.5 mol.
How many litres of oxygen gas are there?

11.5 mol = 22.4 L/ 1 mol = 258 L

150ml x 1 L/ 1000 ml = 0.15 L

0.15 L x 1 mol/ 22.4 L = 0.00670 mol

Extra Notes:
-In conversions mols will almost always equal 1
-Remember to convert values to the appropriate units when asked for a different unit
-Also remember to use significant figures because these are very important in conversions

Molar Mass Mass of Atoms

 Molar Mass
-The mass ( in grams ) of 1 mole of a substance is called the molar mass
- It can be determined from the atomic mass on the periodic table
- Measured in g/mol

Molar Mass of Compounds

- To determine the molar mass of a compound add the mass of all atoms together

Example

Element                  Molar Mass              *Significant Digits

H2O                   2 + 16 = 18.0g/mol  
NO2                  14 + 32 = 46.0g/mol
NaCl                  23 + 35.5 = 58.5g/mol  
FeO                   55.8 + 16 = 71.8g/mol
NaNO3             23 + 14 + 48 = 85.0g/mol

 Converting between moles and mass
- To convert between moles and mass we use molar mass as the conversion factor
- Be sure to cancel the appropriate units

Examples

How may grams is there in 1.5 mol of O2?


1.5mol O2 x 32.0g   = 48g
                  1 mol O2


Example

A sample of HCl contains .54 mol. How many grams of HCl is this?

.54mol HCl x 36.5g     = 20g HCl
                    1 mol HCl


Example

A compound is made of phosphorus and chlorine. It is found to contain 0.200 mol and has a mass of 27.5g
- Determine the molar mass of the compound
- Suggest a possible formula

0.200mol x 27.5g  =  137.5g/mol            Formula = PCl3
                        1 mol

Naming Compounds

Chemical Nomenclature

-Today, the most common system is IUPAC for most elements like,

1. Ions
2. Binary Ionic
3. Polyatomic Ions
4. Molecular Compounds
5. Hydrates
6. Acids/Bases

Chemical Formulas

-Beware of the differences between Ion and Compound Formulas

Eg.


Zn^2+ (The 2+ means an Ion Charge)
BaCl2   (The 2 means the number of Ions)

Multivalent Ions

-Some elements can form more than one ion.
  -Eg. Iron > Fe^3+ or Fe^2+
  -Eg. Copper > Cu^2+ or Cu^1+
-The top number on the P.T. (Periodic Table) is more common
-IUPAC was uses roman numerals in parenthesis to show the charge
-Classical (i.e. Old) systems uses latin names of elements and the suffixes like '-ic' (larger charge) and '-ous' (smaller charge)
  -Eg. Ferric Oxide
            /\
      Refers to Iron (Fe)
      '-ic' refers to larger charge
      So iron's charge would be +3 not +2

Other Classical Names
-Ferr - Iron
-Cupp - Copper
-Mercur - Mercury
-Stann - Tin
-Aunn - Gold
-Plumb - Lead

Eg.  FeCl2 - Ferrous Chloride
       SnO2 - Stannic Oxide
       Pb(NO3)2 - Plumbous Nitrate

Hydrates

-Some compounds can form lattice that bond to water molecules

   -Copper Sulfate
   -Sodium Sulfate                                   Without water, the compounds is often preceeded by 'anhydrous'


-These crystals contain water inside them which can be released by heating
-To name hydrates

1. Write the name of the chemical formula
2. Add a prefix indicating the number of water molecules (mono, di, tri, tetra, penta etc..)
3. Add hydrate after the prefix

Eg. Li(ClO4) 3H2O - Lithium Perchlorate Trihydrate

Molecular Compounds

-Write names of the following compounds

N2O4 - Dinitrate Tetraoxide

Naming Acids/Bases

-Hydrogen compounds are acids
   HCl > Hydrochloric acid

Naming Bases

-Caution and OH
   -NaOH - Sodium Hydroxide

Trends on the Periodic Table

-Elements close to each other on the periodic table display similar characteristics
-There are 7 important periodic trends
1. Reactivity
2. Ion charge
3. Melting point
4. Atomic Radius
5. Ionization energy
6. Electronegativity
7. Density*

Reactivity

-Metals and non-metals show different trends

-Te most reactive metal is Francium; the most reactive non-metal is Fluorine

Ion charge

-Elements ion charges depend on their group (column)

Heres a picture of the Ionic charges:http://www.chemprofessor.com/ptable4.gif

Melting point

-Elements in the center of the table of the highest melting point

-Noble gases have the lowest melting points

-Starting from the left and moving right, melting point increases (until the middle of the table)

Atomic Radius

-Radius decrease to the up and 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 election from an atom

-It increases going up and to the right

-All noble gases have high ionization energy

-Helium has the highest ionization energy

-Francium has the lowest ionization energy

-Opposite trend from atomic radius

Electronegativity

-Electronegativity refers to how much atoms want to gain electrons

-Same trend as ionization energy

Electronic Structure

Drawing Electron Dot Diagrams

-The nucleus is represented by the atomic symbol. 

- For individual elements determine the number of valence electrons.

- Electrons are represented by dots around the symbol.

- 4 orbitals (one of each side of the nucleus).

each holding a maximum of 2e. 

Lewis Diagrams for Compounds & Ions

- In compounds electrons are shared

1. Determine the # of valence e- for each atom.

2. Place atoms so that valence e- are shared to fill each orbital.

Double and Triple Bonds

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

Ionic Compounds

- In ionic compounds electrons transfer from one element to another.

- Cation (metal - positive charge)

- Anion (non-metals - negative charge) 

Lewis Diagrams for Polyatomic Ions

1. Determine the # of valence e- for each atom in the molecule.

2. Subtract one electron for each positive charge.

3. Add one electron for each negative charge. 

Links:

The link giving step by step instructions on how to draw an electron dot diagram (shown in class)

1. http://www.youtube.com/watch?v=y6QZRBIO0-o

more info on Lewis structures of atoms, ions, and compounds.

2. http://www.ausetute.com.au/lewisstr.html

Jomar Delos Santos