Take two pencils and sharpen both the ends. Fill the beaker with tap water. Connect the graphite of pencils to 9v battery and the contact should be good. Use a piece of cardboard to hold the pencils in a vertical position. Now wait for 3 – 4 minutes and observe the electrodes carefully.
a) what do you observe near the graphite of pencils?
b) Name the phenomenon associated with it.
c) What would you add to make water more conductive?
d) which precautionary measure need to be taken?
Answers
Electrolysis is the process by which an electric current is passed through a substance to affect a chemical change. The chemical change occurs when the substance loses electrons (oxidation) or gains them (reduction). In the two experiments listed below, the first reactive substance is water and the second one is a copper sulfate solution.
Electrolysis is used to remove hair, split compounds, and in the manufacturing process to decorate, strengthen, and make metal surfaces more resistant to rust.
Answer:
At the cathode (the negative electrode), there is a negative charge created by the battery. This means
that there is an electrical pressure to push electrons into the water at this end. At the anode (the positive
electrode), there is a positive charge, so that electrode would like to absorb electrons. But the water isn't
a very good conductor. Instead, in order for there to be a flow of charge all the way around the circuit,
water molecules near the cathode are split up into a positively charged hydrogen ion, which is
symbolized as H+ in the diagram above (this is just the hydrogen atom without its electron, i.e. the
nucleus of the hydrogen atom, which is just a single proton), and a negatively charged "hydroxide" ion,
symbolized OH-
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