While passing electric current through a piece of cut potato what helps you to learn that one of the two electrodes is a positive terminal (the anode)?
Answers
Answer:
We have learnt some effects of electric current. List those effects. What effect does the current produce when it flows through a conducting solution? Let us find out.
Take out carbon rods carefully from two discarded cells. Clean their metal caps with sand paper. Wrap copper wires around the metal caps of the carbon rods and join them to a battery . We call these two rods electrodes. (Instead of carbon rods, you may take two iron nails about 6 cm long ).
Explanation:
Chemical Effects of Electric Current
Electroplating
Chemical Effects of Electric Current
We have learnt some effects of electric current. List those effects. What effect does the current produce when it flows through a conducting solution? Let us find out.
Take out carbon rods carefully from two discarded cells. Clean their metal caps with sand paper. Wrap copper wires around the metal caps of the carbon rods and join them to a battery . We call these two rods electrodes. (Instead of carbon rods, you may take two iron nails about 6 cm long ).
Pour a cupful of water in a glass/plastic bowl. Add a teaspoonful of salt or a few drops of lemon juice to water to make it more conducting. Now immerse the electrodes in this solution. Make sure that the metal caps of the carbon rods are outside the water. Wait for 3-4 minutes. Observe the electrodes carefully. You will notice gas bubbles near the electrodes. We call the change taking place in the solution a chemical change.
In 1800, a British chemist, William Nicholson (1753 to 1815), had shown that if electrodes were immersed in water, and a current was passed, bubbles of oxygen and hydrogen were produced. Oxygen bubbles formed on the electrode connected to the positive terminal of the battery and hydrogen bubbles formed on the other electrode.
The passage of an electric current through a conducting solution causes chemical reactions. As a result, bubbles of a gas may be formed on the electrodes. Deposits of metal may be seen on electrodes. Changes of colour of solutions may occur. The reaction would depend on what solution and electrodes are used. These are some of the chemical effects of the electric current.
We decided to test whether some fruits and vegetables also conduct electricity or not. He cut a potato into two halves and inserted the copper wires of a tester into it. Just then his mother called him and he forgot to take out the wires of the tester inserted into the potato. When he came back after half an hour, he noticed that there was a greenish blue spot on the potato around one wire whereas there was no such spot around the other wire.
He was surprised with this observation and along with repeated this activity many times. They found that it was always the wire connected to the positive terminal, which had greenish blue spot around it. They felt that this discovery was very useful because it could be used for identifying the positive terminal of a cell or a battery concealed in a box. They decided to report their finding to a childrens magazine.
Remember that set out to test whether potato conducted electricity or not. What he found was that current produced a chemical effect in the potato. To him this was very exciting. In fact, this is how science sometimes works. You are looking for something and you discover something else. Many important discoveries have been made in this manner.
Electroplating
Recall that a brand new bicycle has shiny handlebar and wheel rims. However, if these are accidentally scratched, the shiny coating comes off revealing a not so shiny surface beneath. You might have also seen women using ornaments, which appear to be made of gold.However, with repeated use, the gold coating wears off, revealing silver or some other metal beneath.
In both these cases, a metal has a coating of another metal. Do you wonder how a layer of one metal can be deposited on top of another? Well, let us try doing it ourselves.