Conductors and Insulators
Conductors –allow electricity to pass through them. Due to free electrons present on their surface. [Metals, Human body]
Insulators – Don’t allow electricity to pass through them. [Air]
Pure water doesn’t conduct electricity. Most of the acids, bases, and salts are conductors. When electrodes are dipped in water and an electric current is passed through them, Oxygen bubbles formed on the electrode connected to the positive terminal of the battery, and hydrogen bubbles formed on the other electrode.
Effects of Electric current
The heating effect of electric current is used in geysers, heaters, irons, etc. The heating produced in a wire depends on its material, thickness, and length. Bulbs have filament of tungsten that emits light when heated at high temperatures, it is also filled with an inert gas like nitrogen or argon.
The magnetic effect of current was discovered by Hans Oersted. This principle is used in electromagnets and electric bells.
Uses of Electric current
Electroplating is a common application of the chemical effects of electric current.
e.g.: Chromium doesn’t rust or scratch so metal is coated with chromium for utensils, and tin is coated with iron in tin cans so food doesn’t come in contact with iron. Iron objects are coated with zinc to prevent corrosion “Galvanization“.
Corrosion is an oxidation reaction.
Oily foods get oxidized if kept in the open and their taste changes [rancidity], due to this they are kept in air-tight containers. Hence, Chips bags are flushed with nitrogen to prevent oxidation.
AC current can be transmitted farther than DC without much loss of electrical energy.
Household devices are connected in parallel.
Fuel Cells
Fuel cells use a reaction of oxygen and hydrogen, porous carbon electrodes, and an aqueous solution of NaOH. Platinum or palladium electrodes are used as catalysts.
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