CHEMICAL EFFECTS

• The possible reasons for the bulb not glowing in an electric circuit are loose connections, a fused bulb, or a used-up cell.
• Conductors are substances which allow electric current to pass through them, examples include all metals, humans, and tap water.
• Insulators are substances which do not allow electric current to pass through them, examples include rubber, wood, and plastic.
• A closed-circuit diagram can be used to test the conduction of current in a liquid using a standard bulb.
• The filament of the bulb in a closed circuit gets heated to a high temperature and it starts glowing due to the heating effect of electric current.
• The current passing through the circuit is too weak, the filament does not get heated sufficiently and it does not glow.
• This can be overcome by using an LED bulb in place of the standard electric bulb in the circuit as LED bulb glows even when weak electric current flows through.
• The full form of LED is Light Emitting Diode.
• There are two wires called ‘leads’ attached to an LED bulb, one lead is slightly longer than the other.
• In a circuit, the longer lead of an LED bulb is always connected to the positive terminal of a battery and the shorter lead is connected to the negative terminal of the battery.
• LED is used to detect weak currents.
• When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection, indicating that the current is flowing through the wounded wire and hence through the circuit.
• Pure water does not conduct electricity, but it can conduct electricity when a pinch of common salt is added to it, as salt solution is conductive in nature.
• An electric current is passed through a conducting solution, bubbles of gas may be formed on the electrodes, deposits of metal may be seen on electrodes, change in the colour of the solution may take place, and the solution may get heated.
• The positive terminal of a battery inserted into a half cut potato turns green.
• The three effects of electric current are heating effect, magnetic effect, and chemical effect.
• When an electric current is passed through an electrolyte, a chemical reaction takes place, this is called chemical effect of electric current.
• An electrolyte is an aqueous solution of a chemical compound, which conducts electric current and at the same time undergoes a chemical change.
• Gold plated or silver-plated metals are used by jewelers to make ornaments.
• Electrodes are the metal wires or plates or rods through which the current enters or leaves an electrolyte.
• Cathode is the electrode connected to the negative terminal of the cell or battery.
• During electrolysis, the anions are discharged at anode by taking electric charges from it.
• Thus, the loss of copper from the solution is restored and the process continues.
• Electrolysis is the process due to which a solution of a chemical compound conducts electric current and at the same time undergoes a chemical change.
• Aqueous solutions of all acids, bases, and salts are non-electrolytes.
• Tin is less reactive than iron and its coating prevents food from coming in contact with iron and thus prevents it from getting spoilt.
• A coating of zinc is deposited on iron to protect it from corrosion and formation of rust.
• Chromium has a shiny appearance and does not corrode, it resists scratches but is expensive and may not be economical to make the whole object out of chromium.
• Ions are the electrically charged atoms or group of atoms formed when a chemical compound is dissolved in water.
• Iron is used in bridges and automobiles to provide strength.
• From the other electrode, a copper plate, an equal amount of copper gets dissolved in the solution.
• Chromium plating is done on various objects such as car parts, bicycle handlebars, bathroom taps, kitchen gas burners etc.
• Electroplating is the process of depositing a layer of desired metal on another material by means of electricity.
• Voltameter is an apparatus in which electrolysis is carried out such that it consists of a vessel, two electrodes and an electrolyte.
• The free copper ions get drawn to the electrode connected to the negative terminal of the battery (cathode) and gets deposited on it.
• Anions are the negatively charged ions formed when a chemical compound dissolves in water.
• Cations are the positively charged ions formed when a chemical compound dissolves in water.
• When electric current is passed through copper sulphate solution, copper sulphate dissociates into copper and sulphate ions.
• During electrolysis, the cations are discharged at cathode by taking electric charges from it.
• Iron cans for storing food are electroplated with tin.