Chemical effects of electric current

1. A
P.P.T
ON
CHEMICALEFFECTS
OF
ELECTRICCURRENT

2. KNOW ABOUT CHARGES
To understand electricity and related terms, it is important to
understand what charges are. The charges that carry electricity
are present in basic unit of matter, that is in atoms. Atoms are the
smallest particles of matter which combine together to form
matter. Atoms are further composed of particles called electrons,
protons, and neutrons. The protons are positively charged,
electrons are negatively charged and neutrons are neutral. The
total charge of an atom is neutral. The protons and neutrons
remain in the nucleus, whereas the electrons move around the
nucleus.
All metallic elements have ‘free electrons’ in the outermost orbit.
An electric current is set up when these free electrons move from
one atom to another.

3. WHAT IS ELECTRIC CURRENT?
Electric current is the flow of electrons.
MORE ABOUT ELECTRIC CURRENT :-
The passage o electric current through
substances is called conduction.
Some materials allow electric current to pass
through them whereas others do not. Also,
conducting materials may behave differently
when electric current is passed through them-
some are decomposed and some are not.

4. CONDUCTORSANDINSULATORS
All substances do not allow electric current to pass through them. Based on this
ability, substances are divided into two categories- conductors and insulators.
Substances that allow heat or electricity to flow through them readily are called
conductors. For example, metals and some non-metals such as graphite are
good conductors of electricity.
Substances that do not allow the free flow of charges through them are called
insulators. For example, dry wood, plastic, rubber, wool and cotton are
insulators.

5. DIRECTION OF ELECTRICCURRENT
Charges flow from the positive
terminal of the source to the negative
terminal. That is why the flow of
current in a circuit is marked from
the positive terminal to the negative
terminal using arrowheads. This
current is also known as conventional
current.

6. CHEMICALCHANGESDUETOELECTRIC
CURRENT
When electric current is passed
through solutions, you might
notice bubbles of gases. This is
due to the occurrence of a
chemical change. Change in the
colour of solution, precipitation
and change in temperature of
solution can also be observed
because of chemical reactions.

7. ELECTRICALCONDUCTIVITY
Electrical conductivity is the ability of a substance to allow the flow of
electric current. A substance may have a good conductivity
irrespective of whether it is a solid or a liquid. A liquid with a good
conductivity is called an electrolyte, and the one which is incapable of
conducting electricity is called a non-electrolyte.

8. Electrolyte Non-electrolyte
Tap water Distilled water
Sulphuric acid Sugar solution
Nitric acid Spirit
Hydrochloric acid Acetone
Common salt solution Benzene

9. ELECTRICALCONDCTIVITYOF WATER
Water that is not in the pure form
becomes a good conductor of
electricity because of the presence of
impurities. It is always advised that
while handling electrical appliances we
should ensure that our hands and feet
are not wet, so that electric current
does not pass through our body and
we do not get an electric shock.

10. ELECTRICALCONDUCTIVITYOF
OTHERLIQUIDS
Many liquids are good conductors
of electricity. Several acids and
bases when dissolved in water
become good conductors of
electricity. Lemon juice, vinegar,
aqueous sodium chloride and
aqueous potassium chloride are a
few examples.

11. EFFECTS OF IMPURITIES ON
ELECTRICAL CONDUCTIVITY OF WATER
Although distilled water does not conduct electricity, ordinary tap water is a
good conductor. This happens because the dissolved salts in the tap water
increases the conductivity of water. For an electric current to flow, charged
particles should move freely. These particles are also known as charged carriers
since they carry the charges. In the metals, the charged carriers are the
electrons. In liquids, these charged particles are ions(negatively or positively
charged atoms).

12. ELECTROLYSIS
We know that it is possible to pass electric
current through water. When electric current is
passed through water, it is possible to break it up
into its individual components- oxygen and
hydrogen. By passing electric current through
aqueous common salt (sodium chloride), it is
possible to split it into sodium and chlorine.
The process by which a substance is
split into its components when electric
current is passed through it is called
electrolysis. In other words, it is the
chemical effect of electric current
whereby electric current causes a
chemical change in the substance
through which it passes. An electrolyte,
in liquid state or dissolved in water,
conducts the current and undergoes a
change during electrolysis.

13. The two plates or rods
through which the current
enters and leaves the
electrolyte are called
electrodes. The electrode at
which the current enters the
electrolyte is called the anode
and the electrode at which it
leaves is called the cathode.
The anode is positively
charged while the cathode is
negatively charged. The
arrangement consisting of a
vessel, the electrolyte, the
electrodes and a source of

14. ELECTROLYSISOFCOPPERCHLORIDE
When copper chloride solution is taken in a beaker and two
carbon electrodes are placed in it to form a circuit, current
flows through the solution once the connection s complete. As
current passes through the circuit, the ammeter shows
deflection. Ammeter is a device used to measure current. After
a while, bubbles of a gas are observed at the anode. This gas
smells of bleaching powder and is easily identifiable as
chlorine. The surface of the cathode becomes reddish due to
deposition of copper. After a while as copper chloride splits into
copper and chlorine, the bright blue colour of the copper
chloride solution starts fading.

15. ELECTROPLATING
Electroplating is a common application of electrolysis. The process of
depositing a thin layer of a metal on any conducting substance by the
process of electrolysis is known as electroplating. For example,
chromium coating is done on car parts, bath taps, wheel rims, etc.
In electroplating, the object to be electroplated is made the cathode
(negative electrode)by connecting it to the negative terminal of the
battery. The metal which has to be deposited is made the anode (positive
electrode)by connecting it to the positive terminal of a battery. The
electrolyte is usually a salt solution of the metal to be coated. On passing
electric current, the object gets coated with the desired metal.

16. ACTIVITY
Aim: To demonstrate electroplating
Material required: iron key, copper plate, silver bar, solution of copper
sulphate, beaker, three 9-V cells, wire
Procedure: Connect the key, copper plate and the battery with the wire
to form a circuit. The key should be connected to the negative terminal
of the battery and the copper plate to the positive terminal. Dip them in
the solution of copper sulphate in a beaker and observe.
Observation: Once he circuit is connected, the process gets started and
after some time, it is seen that the key gets a coating of copper.
Conclusion: The positive charges, that is copper ions, move towards the
cathode, and the key is electroplated.

17. THANKYOU