Goals: In this lab, students will study different aspects of enzyme activity by doing the following: ... 3. CAUTION: The water bath contains hot water. Steam will burn. 4. Be careful when using test tubes in hot water bath. Use a test tube holder. La
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Idea Transcript
Lab 35 - Iron-Copper(II) Chloride Reaction In this experiment, a single replacement reaction will be investigated. Iron nails will react with a copper(II) chloride solution. When this reaction occurs, copper metal and one of two other possible products is formed: iron(II) chloride or iron(III) chloride. By determining the masses of iron consumed and the mass of copper formed it will be possible to deduce which iron chloride was produced. Once the identity of the iron chloride has been determined, the equation for the reaction will be written. Procedure, Day 1 1. Obtain the mass of an empty, clean, dry 250 mL (or 100 mL) beaker. Label the beaker with your initials using a wax pencil. 2. Weigh 3.00 g of copper(II) chloride into the beaker. In the event 3.00 g of copper(II) chloride is not used, record the exact mass that was used. Dissolve the copper(II) chloride in 20 mL of water. Use a glass stirring rod to mix. Make sure that all of the copper(II) chloride has dissolved before proceeding. 3. Obtain and mass 2 clean, dry iron nails. 4. Place the nails in the beaker with the copper(II) chloride solution. Allow the reaction to occur for about 30-40 minutes. 5. Pick up the nails, one at a time, with a pair of tongs. Using a wash bottle, wash all of the reddish-brown material from the nails back into the reaction beaker. 6. Put the nails aside to dry in a safe place. After the nails are dry, mass them and then dispose of them in the trash (not the sink). 7. Carefully decant (pour off the liquid, leaving the solid behind in the reaction beaker) the solution from the reddish-brown material remaining in the beaker. Your teacher will demonstrate the "pour-down-the-stirring-rod" technique. 8. Wash the remaining solid with about 25 mL of water (add the water, swirl, allow solid to settle) and decant again. Repeat this washing procedure 4 or 5 times. Be sure to retain the reddish-brown material in the reaction beaker. 9. Wash the solid with about 25 mL of 1M HCl. Decant and wash one final time with 25 mL of water. Decant. 10. Put the beaker on the shelf above the lab bench to dry until the next lab period.
Procedure, Day 2 11. Mass the beaker with the solid copper. Put some tap water into the beaker, stir up the solid and pour the solid and water into the trash. Clean up and put all equipment away.
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Questions (Show your work!) 1. Determine the mass of iron lost by the nails. 2. Calculate the number of moles of iron that reacted. 3. Determine the mass of copper formed. 4. Calculate the number of moles of copper formed. 5. Determine the mole ratio of iron reacted to copper formed. 6. Write and balance the two possible equations for the reaction that occurred (refer to the Introduction). 7. Using the results from #5, explain which product was produced and write the appropriate balanced equation that describes this reaction. 8. List some possible sources of error in this experiment. Don’t just say “human error” or “measuring error” – be specific! In other words, go back over the procedure and think about where you thought it was difficult to be “perfect” in this experiment.
Lab 35: Post-Lab Questions Help
1. Mass of iron lost by the nails. In other words, how many grams of iron from the nails reacted? 2. Moles of iron reacted.
Convert the grams of iron reacted (answer #1) to moles.
3. Mass of copper formed.
In other words, how many grams of copper were in the beaker at the end?
4. Moles of copper formed
Convert the grams of copper reacted (answer #3) to moles.
5. Mole ratio of Fe : Cu
Divide each of your answers from numbers 2 and 4 by the lowest. It is similar to an empirical formula.
6. Write two equations. One will be for the reaction between copper(II) chloride and iron to form copper and iron(II) chloride. The second reaction will be for the reaction between copper(II) chloride and iron to form copper and iron(III) chloride. Balance each reaction. 7. Rewrite the equation that matches your answer from number 5. In order to do this, look at the mole ratio of iron to copper in the two equations in number 6. They are different for each equation. Your data should be closer to the ratio from one of the equations than it is to the other. 8. Be sure these are things that would make a difference in the results. In other words, think back to things you did that might have made a difference in the results.