Lemon batteries

The site http //antoine.frostburg.edU/chem/senese/l 01/redox/faq/lemon-battery.shtml cites details of how to make a battery from a lemon. 

For obvious reasons, lemon batteries are not a convenient way to power a portable device, such as a cell phone. Scientists and inventors have worked to develop a variety of batteries that are inexpensive, compact, and easy to store and to carry. Our society uses vast numbers of batteries. 

The reaction in the lemon battery is the reduction of copper ions (a little bit of copper dissolves from the copper penny in the acidic lemon juice) and the oxidation of zinc into zinc ions—the thermodynamically more stable state. Because the reaction is moving toward a more stable state, it can produce electricity as a voltaic cell. An electrolytic cell is the antithesis of the voltaic cell. In the voltaic cell, a chemical reaction is used to produce electricity. In an electrolytic cell, electricity is used to produce chemistry. A demonstration electrolytic cell can be set up as follows. 

How does the lemon battery produce electrical energy The lemon itself is a container for a solution of electrolyte—the lemon juice. As you know, lemon juice is sour that is, it is acidic. The hydrogen ions from partiaUy dissociated citric acid give it a sour taste and also provide the ions for conduction of charge through the lemon battery. The two dissimilar metal strips are the electrodes at which an oxidation reaction and a reduction reaction take place to provide the battery s power source. 

In the lemon battery shown in Figure 17.9, a different chemical reaction occurs at each of the metal-strip electrodes. The electrode made of the metal that is more easily oxidized becomes the anode—the electrode at which the oxidation reaction occurs. The second electrode becomes the cathode, and a reduction reaction proceeds at its surface. The substance in a lemon that is most easily reduced is the abundant hydrogen ion of the electrolyte. When these two reactions occur together, in the same cell, they combine to produce a spontaneous redox reaction. This type of reaction is represented by the equation below, where M is the metal that is oxidized. 

In this model of a lemon battery, the level of the electron sea is raised or lowered by the chemical reactions at the electrode surfaces, creating a potential difference across the battery. A spontaneous oxidation reaction raises the electron pressure (potential) at the anode, and a spontaneous reduction reaction reduces the pressure at the cathode. The "sea level" in the lemon juice is uniform throughout and is intermediate between the levels at the two electrodes. 

What is the purpose of the lemon used in making a lemon battery If you didn t have any lemons available for constructing your battery during that NBA final, what else could you have used ... 

MiniLab 2 Why should the metal pieces used as electrodes in the lemon battery be cleaned with steel wool ... 

Connect the nail of the first lemon to a terminal of a voltmeter using an alligator clip and a piece of wire. Connect the penny of the third lemon to a terminal of a voltmeter in the same way. Determine the potential of the lemon battery. 

Electrochemistry - in a small group you can show the potential in a potato or lemon battery using a volt meter, but it may be less useful in a larger group. 

All common batteries convert chemical energy into electrical energy by means of an oxidationfeduction reaction. A battery can be made by placing a strip of copper and a strip of zinc into a lemon This lemon battery produces enough current to power a small clock. 

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