Electrolysis of Water and Fuel Cells Vanderbilt Student Volunteers for Science Spring 2016

Conversions of Electrical Energy to Other Forms Electrical Energy is Converted to: Mechanical Thermal Light Chemical Sound in these Examples Motors Heaters, toasters Light bulbs Electrolysis of water Doorbells

Tell students to: Attach the alligator clips from the 9-volt battery to the short end of the electrodes. Submerge the electrodes in distilled water (sit lid on top of the jar). Results Distilled water cannot conduct electricity, so there is no reaction. A. Electrical Energy  Chemical Energy (Electrolysis)

Tell students to: Remove the electrodes Add 1 mini tsp sodium sulfate salt into jar of distilled water. Stir with toothpick. Submerge the electrodes into the salt water. Conclusion Electrical energy comes from the battery. The electric energy is converted into chemical energy to decompose water. Water is decomposed into hydrogen and oxygen gases. Only ionic solutions will conduct electricity. B. Electrical Energy  Chemical Energy – Electrolysis Distilled water + sodium sulfate conducts electricity  Decomposition of water Negative Hydrogen gas bubbles (2X as many) Positive Oxygen gas bubbles

C. Fuel Cell Fuel Cell Experiment Students will work with a VSVS member. There are 4 sets of materials, so divide the class accordingly A. Examining the Fuel Cell B. Hydrogen Production Students use the hand crank to produce hydrogen and oxygen gas, and observe the different volume each gas holds. C. Fuel Cell Car Students learn how the fuel cell car operates, and observe how the hydrogen is converted back to water.

Materials needed for each group 1 reversible fuel cell 1 model car 3oz bottle of distilled water 1 hand crank with built in patch cables 6 oz. cup 1 plastic plates

Activity A: Examining the fuel cell 1.Pass out the handout to the students –There is a student version and a volunteer version. The student version has an image of the fuel cell and the fuel cell car, along with numbers identifying the important parts of each. The volunteer version has more detailed descriptions of the identified parts 2.Help students identify all parts of the cell and the car

Activity A: Preparing the fuel cell 3. Place the fuel cell upside down on a plastic plate placed on a flat surface 4. Remove the stoppers and set them next to the fuel cell 5. Pour distilled water into both storage cylinders until the water reaches the tops of the small tubes in the center of the cylinders –Be careful to pour the water around the outside of the cylinder, not into the small tube in the middle –Here –Not here

Activity A: Preparing the fuel cell 6.Tap fuel cell lightly to help water flow into the area surrounding the membrane and metal current- collecting plates 7.Add more water until it starts to overflow into the tubes in the cylinders 8.Place the stoppers back onto the cylinders. Make sure no air is trapped inside the cylinder. (However, small air bubbles will not cause problems.) 9.Turn the fuel cell right side up –This size of bubble is ok

Activity B: Hydrogen production 1.Attach the red cable from the hand crank to the banana jack positive terminal (red). Then attach the black cable from the hand crank to the banana jack negative terminal (black). 2.Rotate the hand crank (students may do this, but warned to do it carefully) to convert water into hydrogen and oxygen. Students should observe water displacing out of the outlet tube and into the open container above as gas bubbles form and collect in the storage cylinders –Water is displaced up here –Hydrogen gas collects here 3.Rotate the hand crank in full circles about 50 times (students may do this). They should be able to see a small bubble in the hydrogen tank.

Activity C: Fuel Cell Car 1.Detach the patch cables from the fuel cell 2.Being careful not to spill the overflow water, clip the fuel cell into the notches on the car 3.Place the car on the cup so that the wheels are touching neither the cup nor the ground

Activity C: Fuel Cell Car 4.Plug the cables from the car into the cell (red to red and black to black). The car will begin running as soon as both cables are plugged in. 5.Let the car run until it stops 6.Once the fuel is used up, have the students examine the two water tanks