December 3 - Moles of Iron and Copper Lab

Today we were assigned to do a lab. In this lab we had to determine the number of moles of copper produced in the reaction of iron and copper (ii) chloride, the number of moles of iron used up in the reaction of iron and copper (ii) chloride, the number of atoms and formula units involved in the reaction and, the ratio of moles or iron to moles of copper. 

This is our procedure:

• First of all we weighed a dry 250 mL to find its mass.
• Then we added about 8 grams of copper (II) chloride crystals into the beaker and weighed it.
• After, we added 50 mL of water to the beaker
• Then weighed the 2 nails and placed them into the copper (II) solution
• Then saw a formation happening to the nails and after a couple of minutes we carefully used tongs to pick up the nails and removed any of the remaining copper from it.
• After we dried the nails and removed the copper, we then weighed the nails again to find its new mass.
• The excess solution was poured into the beaker carefully through a funnel and filter paper.
• At last we placed the copper in a drying oven and then find the new mass of the beaker and the copper 

1. Janine Roldan

Multi-Step Conversion Review

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