Embedded Files
This lab will go in your lab book. Follow the directions below to complete the lab.
Purpose (put into lab book)
The purpose of this experiment is to learn how to perform an electrolysis of water and (Honors only:) to calculate the current of the battery being used.
Background (summarize into lab book)
In your lab book define the following terms that will be used during this lab: electrolysis, cathode, anode, electrolyte, oxidation, and reduction.
Materials (put in lab book)
Read the procedure. Write down all equipment and chemicals you will need for the lab.
Procedure (read - do not put in lab book)
Recreate the apparatus with test tubes to collect the bubbling gas (See photo 1 below). Be sure that it is directly above the pins because this is where the gas will be produced and you need to catch all the gas bubbles.
Fill your plastic beaker with 10 mL the sulfuric acid (this will help the water to conduct because pure water is not a good conductor - YOU WILL NOT INCLUDE THIS IN YOUR PICTURE) and the rest of the way with water.
Pour the solution into the test tubes and be sure to fill completely. Using your fingers, stopper the top of the test tubes, invert them and place them into the solution. You need to make sure that there are no air bubbles in the test tubes. (See photo 2 below)
Connect the black wire to the negative end of the battery and one of the pins. Connect the red wire to the positive end of the battery and then to the other pin. (See photo 3 below)
Begin timing. Let it run for twenty minutes. While you are waiting during the twenty minutes, start working on the conclusion questions.
Mark the location of the gas on each of the test tubes using the wax pencil.
Measure the volume of gas at the line using water and a graduated cylinder.
Photos of Lab
Photo 1: Test tube apparatus used to collect the gases at the anode and the cathode.
Photo 2: Test tube apparatus filled with water and placed into the water and on top of the electrodes to catch the gases.
Photo 3: Full set up. Battery hooked to the electrodes. In this lab the electrodes were the metal pins.
Data (put into lab book)
If you are absent, click here.
Volume of Hydrogen collected
(mL)
Volume of Oxygen collected
(mL)
Conclusion (answer in lab book)
Draw a diagram of your lab set-up (exactly as it appears in this lab). Label the positive and negative end of the battery, show the flow of electrons, label the anode and the cathode, show the ions and their movement in the beaker, and show what is produced in each test tube.
Write the two half reactions. Indicate which is the oxidation / reduction.
Write the steps describing what is happening during the electrolysis, starting with the release of the electrons from the battery.
In a perfect experiment, you should get twice as much hydrogen as oxygen gas. Why is that the relationship between the oxygen and hydrogen gas produced?
We usually don't get a two to one ratio for the hydrogen to oxygen. We usually get a lot less oxygen. Look at the pins. Why do you think that is the case?
(Honors) Using the volume of hydrogen that was produced calculate the current produced by the battery.
What is an error in this lab and how would you correct it?
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