Set up the Hoffman apparatus with its attached power source. 6-V to 9-V DC source, such as a transistor batteryįollow normal laboratory safety precautions.Hoffman apparatus (or U-tube fitted with 2-hole stoppers and platinum Nichrome electrodes Bent wires in inverted test-tubes will also work.).To reinforce concepts,have students predict in each case which of the two metals will be thecathode and which will be the anode.ĭemonstration 3: Electrolysis ofWater in Color Try other fruit/vegetables with thesame metals, and other combinations of metal strips. Experiment with placing the metal strips atvarious distances from each other. Connect the strips to the voltmeter with connecting wires. Wash hands thoroughly when the demonstrationis completed.Ĭut the fruit sample in half and insert two unlike metal strips intoit. Materials Metal strip of zinc, copper, aluminum, iron, tin, lead, 1 cm x 3 cm Voltmeter 2 Connecting wires with clips on both ends Firm fruit/vegetables (such as potato, lemon, grapefruit, orange)ĭo not eat these materials. To show that different combinations of electrodes produce differentelectric potentials and that some food materials can serve as electrolytes. Thisprocedure avoids contamination and the need for a salt bridge, giving instantresults.ĭemonstration 2: Fruit and VegetableBatteries Substitute a different metal on the alligator clip untilthe electric potential of each of the six combinations is measured. Touch the proper electrode to its own metalion solution. Attach two different metal electrodes to alligatorclips wired to the voltmeter. Place one drop of each metal ion solution oneach of the four corners. Add some KNO 3 solution to the center of the cross, allowingit to saturate the paper. Use accepted procedures for disposingof heavy-metal solutions.Ĭut the filter paper in the shape of a cross. High-impedance voltmeter that will read 1-2 V.Dropper bottles of 0.1 M solutions of KNO 3, and Mg 2+, Zn 2+, Sn 2+, and Cu 2+ as chloride ornitrate salt solutions.To demonstrate the ability of chemical reactions to produce electricity.The electric potential produced depends on the nature of the metal/metalion half cell.
0 kommentar(er)
