Experiment: Moles of Iron and Copper
Introduction: The mole is a unit for analyzing chemical reactions. The mole is equal to 6.02 X 10 23 particles, also known as Avogadro’s number of particles. More important than the number of particles in a mole, is the mass of a mole of any compound or element. It is the mass in grams corresponding to the molecular or atomic mass. For example, the mass of one mole of copper atoms is 63.5 grams the mass of one atom of copper is 63.5 amu. Similarly, the mass of one molecule of water is 18.0 amu; the mass of one mole of water molecules is 18.0 grams.
Purpose:
1. Determine the number of moles of copper produced and the number of moles of iron used in the reaction of iron and copper (II) chloride.
2. Calculate the ratio of moles of iron to moles of copper.
Materials:
2-100 mL beakers wash bottle
stirring rod
crucible tongs
balance
hot plate
steel wool
paper towels
safety goggles
lab apron
copper(II) chloride
2 iron nails
1 M hydrochloric acid (HCl)
water
Procedure:
1. Put on your goggles and apron. Put your name on a 250 mL beaker then carefully mass and record.
2. Add approximately two grams of copper (II) chloride to the beaker that has your name written on it.
3. Add about 100 mL water and stir to dissolve all of the copper (II) chloride. Record the appearance of this solution. (Copper ions give solutions a characteristically blue color)
4. Obtain two clean, dry nails. Shine them with steel wool. Mass these nails together and record in your data table.
5. Place the nails in the copper solution. Leave the nails undisturbed for approximately 15 minutes. (Record any changes in appearance).
6. Use tongs to pick up the nails, one at a time. Rinse any remaining copper from the nails directly into the beaker in which you did the reaction. If you need to, scrape any copper off with a stirring rod. Make sure as much copper as possible goes into the beaker.
7. Set the nails aside to dry. Record the mass of the nails together before returning the nails to the teacher.
8. Carefully decant the liquid from the solid. (Decant means to pour off the liquid from a container that holds both solid and liquid.) Pour the liquid into another beaker. This is the waste beaker. The goal here is to save as much of the solid copper as possible.
9. After decanting, rinse the solid copper with about 15 mL of water then 15 mL of hydrochloric acid and then one more time with water.
10. After the final wash and decant, place the beaker with the copper on a warm hot plate.
11. Wash hands and clean up.
12. Return to lab in 24 hours for a final mass of the copper and the beaker.
13. Place copper in the trash and clean the beaker.
Pre-lab requirements:
1. Read the lab procedure. Answer the pre-lab questions.
2. Create a computer drawn data table to collect all of the required data and observations for the lab.
Pre-lab questions:
1. How many moles are present in a sample of 34.0 g of iron metal?
2. What is the mass of one mole of copper?
3. Whys is the washing of copper necessary to this experiment?
4. Define the term decant.
5. How will you be able to determine the mass of iron lost from the nail during the reaction?
Post-Lab questions:
1. Create a word equation showing the reactants used and the products formed.
2. Describe the all of the color changes you observed. For each change give a suggestion as to what is occurring to the chemicals in the reactions. (Use a drawing if necessary.)
Calculations:
Include all of the following, be sure to label each calculation for clarity.
a. the amount of copper produced (in grams and moles)
b. the amount of iron used from the nails (in grams and moles)
c. a mole ratio of iron to copper (whole numbers-divide the smallest # into each of the numbers so one of the values will equal 1)