The Determination of a Mole Ratio
A mole ratio can be determined theoretically using a balanced chemical equation. A mole ratio can also
be determined through the results of an experiment. In this lab, you will determine a mole ratio between
Iron and Copper. The experimental results should be the same as the theoretical ratio. This depends
upon how well you perform this laboratory experiment.
Materials:
250 ml flask, funnel, 400 ml or 600 ml beaker, stirring rod, ring clamp, ring stand, wire gauze, filter paper,
100 ml graduated cylinder, Bunsen burner, wash bottle filled with deionized water.
Chemicals: CuSO4 Steel Wool, Deionized water
Procedures:
1. Weigh a clean dry 250 ml flask on the balance, record the mass on the data sheet.
2. Add between 15.0 and 16.0 grams of CuSO4 to the flask. Make sure you record the exact amount you
placed in the flask.
3. Using your graduated cylinder, add 200 ml of deionized water to the flask. Swirl the flask contents to
dissolve the CuSO4 completely. Just in case you must heat the mixture to dissolve all the material, set
up your ring stand, ring clamp, wire gauze and Bunsen burner. If all the material does not dissolve in 5
minutes then heat the mixture.
4. Mass out about 3.0 grams of steel wool. Record the exact mass on the data sheet.
5. Add the steel wool to the solution. Using your stirring rod, stir the flask for 5 to 10 minutes or until the
steel wool appears to break down and has changed color. Using your wash bottle, wash off any
particles that are on the stirring rod into the flask. You do not want to lose any solid.!!
6. You are ready to filter your mixture. Set up your filtration, use your 1st lab to help you properly set up
the filtration. If you used your ring clamp to heat the flask, it may still be hot, cool it down by placing
regular water on it so it will not melt the funnel. MAKE SURE YOU MASS YOUR FILTER PAPER
AND RECORD ON THE DATA SHEET BEFORE YOU PLACE IT IN THE FUNNEL!!!!
7. Make sure all the solid is in the filter paper. You do not want to leave anything in your flask. Once you
have finished filtering, discard the liquid that is in your beaker down the drain. Carefully remove the
filter paper from the funnel and place it into the beaker. Label your beaker with your names and place
it on the side so it will dry. Clean up your lab.
Next Day
8. Mass the dried paper and copper residue. Record your mass on your data sheet. Discard the filter
paper in the garbage.
Data Sheet:
1.
2.
3.
4.
5.
6.
7.
Mass of Flask
Mass of Flask and CuSO4
Mass of CuSO4 (2-1)
Mass of Steel Wool (Fe)
Mass of Filter Paper
Mass of Filter Paper and Cu
Mass of Cu
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Calculations:
1. Determine the moles of Fe.
2. Determine the moles of Cu.
3. Determine the mole ratio of Fe:Cu You will have 2 small numbers from calculation 1 & 2. To get
these values to a whole number ratio, divide the lowest mole to both numbers. You will have a 1 to what
ever you come up with ratio. This is your Experimental Ratio between Fe and Cu.
4. To determine the theoretical ratio, you must have a balance equation. The equation is:
Iron + Copper II Sulfate ---- Cu + Iron II Sulfate
a. Write the formulas for the reaction.
b. What type of reaction is this?
c. Balance the reaction.
d. What is the theoretical mole ratio between Iron and Cu?
5. Determine the percent error use:
Theoretical – Experimental x 100 = %
Theoretical
6. If your error is high than 25%, explain why it is such a high error.