HOW TO MAKE A POTATO CLOCK Separate the two potatoes. Each potato works as a galvanic cell, releasing electrical energy through chemical reactions.[1] Call one potato A (or 1) and the other potato B (or 2). • The bulk of the potato serves as a case for the cell, holding everything in place. The potato juice serves as the electrolyte, in which charged atoms and molecules called ions dissolve and can flow over time.[2] The dilute phosphoric acid in it also provides hydrogen ions for the reaction. • Some atoms (or molecules) strongly attract extra electrons and become negatively charged ions, called anions (an-ions); others are easily stripped of some electrons and become positively charged cations (cat-ions). Each element attracts electrons with different force, due to the differing charge of protons with which their nucleus attracts electrons and the manner in which the marginal valence electrons arrange themselves around the nucleus and other electrons.[3]. The potato juice has dilute phosphoric acid[4], some of which dissolves dissociated into as hydrogen cations (basically) and phosphate anions.[5] Place one copper nail or wire piece into each potato ensuring that the nails dont touch. At this stage it is really important to understand that this experiment will work only if the galvanized nails and the copper nails/wire are as far apart as possible on the potato because the distance between them is Remove the battery compartment lid from the clock. If there is already a battery in it, remove it. Take notice of the batterys polarity in relation to how it connects to the clock. what gen Connect the first jumper wire from copper nail or wire of potato A to the positive terminal of the clock. To do this, take one jumper lead and attach the alligator clip to the copper nail or wire and then the other ends alligator clip to the positive terminal (denoted by the symbol + ).erates the power.[6] Connect the second jumper wire from the galvanized nail of potato B to the negative terminal of the clock, denoted by the symbol -. • When you stick the zinc electrode (the plating on the galvanized nail) and the copper electrode (the copper nail or wire) in the potato, each metal, having less electron affinity than the hydrogen ions, would tend to have its atoms stripped of their electrons by the hydrogen ions. The neutral hydrogen atoms would join together into hydrogen gas molecules and escape; the metal cations would tend to disperse away and more hydrogen diffuse in to continue the reaction slowly bubbling away the acids hydrogen and consuming the metals. • Zinc has even less electron affinity than copper. So, if you connect the electrodes with a conductor[7], the wire, some electrons will tend to flow in it from the zinc to the copper.[8] • The removal of some electrons from the zinc electrode then that will make a few of its atoms fall off as cations which are positive and be dissolved away. The excess of electrons at the copper will make hydrogen preferentially take them up there, but also tend to make the copper keep its electrons and not be corroded (or, more precisely, shift the reaction equilibrium so that the copper ions that do fall off tend to regain electrons and reattach for little or no net corrosion).[9] The removal of electrons from the copper and the addition of electrons to the zinc would tend to build up areas of electric charge that would retard the reaction. But more electrons keep conducting through the wire, and more hydrogen and zinc ions keep dispersing through the potato to maintain fresh solution at each electrode, to keep the reaction going. The force with which the copper thus draws the electrons can be used to do work, like run a clock.[10]. Connect the third jumper wire to the galvanized nail of potato A. Then connect its other end to the copper nail of potato B. By this stage all three jumper leads are interconnected and the clock should be functioning. Check the clock. It should now be running on potato power. • The reaction slows as the zinc metal and the hydrogen ions are depleted. The force with which the hydrogen pulled the electrons off the zinc, in a very roundabout way, is what the cell makes available to you for work--with a little being wasted, of course.[11] • Wiring the potato cells end-to-end makes a series circuit, pulling the stream of electrons through the clock with twice as much force as one potato would apply.[12]It also makes them properly called a battery, because youre using more than one electrochemical cell.[13] • Once its working, why not set the time on the clock to the current time! • If the clock doesnt work, check that all connections are secure and in the right order, and double-check the polarity of the clock. If it still doesnt work, your clock might require more power than the very little a vegetable battery can provide.[14]You can satisfy yourself that the battery is producing some electricity with amultimeter and measuring its voltage (electrical pressure) and current (electrical flow, amps). If you have to choose scales, choose very low ones: these batteries produce a volt or two and a few milliamps.
Posted on: Mon, 17 Mar 2014 08:21:21 +0000
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