class ninth

1.Fill in the blanks:
(i) There are large spaces between the molecules of gasses.
(ii) The theory Formulated to explain the composition of a gas is called Kinetic theory.
(ii) All material objects are made up of small particles which are always in motion.
(iv) The three states of a substance solid, liquid and gas are similar to one another chemically but
are different physically.
(v) The pressure of a gas is due to collision of its molecules with the wall of the container.
(vi) Among solid, liquid and gas, the highest value of kinetic energy is possessed by the particles of
a gas.
(vii) The escape of air from a balloon is called diffusion
2. Tick the correct answer from the following statements:
(i) According to Kinetic theory, the basic difference between the solids, liquids and gas is due to
(a) The difference in the velocities of the particles present in them. ( √)
(b) The chemical properties of the particles present in them.
(c) The size of the particles present in them.
(d) The size of the particles present in them.
(ii) The molecules of ice have
(a) an ionic bond present in them.
(b) an covalent bond present in them.
(c) an co-ordinate covalent bond present in them.
(d) Vander Walls forces present in them. ( √)
(iii) How heating a liquid will effect its evaporation.
(a) Decreases (c) Increases ( √)
(b) Remain the same (d) Initially increases and then decreases upon further heating
(iv) 00 C temperature of water is called its.
(a) Melting point (c) Boiling point
(b) Freezing point ( √) (d) Both melting and freezing point
(v) Cooling the vapors of some compounds change them directly into solid state. This phenomenon is called:
(a) Evaporation (c) Sublimation ( √)
(b) Condensation (d) boiling
(vi) The free movement of molecules in liquids makes them:
(a) Conductors (c) Non-conductors
(b) Non-electrolytes and non-conductors (d) Electrolytes ( √)
3: It is easy to compress air as compare to water. Why?
Answer: Air in gaseous physical phase and having large spaces between gas molecules, so by applying pressure, it can easily be compressed but water in liquid phase is having very less inter molecular spaces so difficult to compress.
4: Explain the following phenomena:
(i) How dose a liquid evaporate?
(ii) What is the condition of the particles of a solid at its melting point?
(iii) A gas neither has a fixed shape nor a fixed volume.
Answer: (i) Molecules having enough energy (i-e enough energy required to overcome cohesive forces) detaches them from
Bulk (Source/Reservoir) .This process occurs at all temperature and is called evaporation. Or Escape of
water molecules from any general surface is called evaporation.
(ii) The assembly in case of solid(Crystalline) distorts and the molecules/atoms of substance moves randomly
upon heating ,the temperature on which melting or above stated process occurs is called melting point.
(iii) Gas particles/molecules have negligible or no attractive force among them and they are in continuous random motion
So the gas kept in any container having any size or shape just adjusts it self and acquires the same shape.
5. Explain the difference between boiling point and evaporation?
Answer: Boiling Point:
When the vapour pressure of the liquid equalizes with the external atmospheric pressure then
the temperature of the sample is called boiling point of that particular substances / product.
Evaporation:
Escape of water molecules from any general surface is called evaporation. It occurs at all temperature.
6. A pure solid object is initially melted and then cooled slowly. During cooling, the temperature is noted after an interval of one minute and the following observations are made.
Time(Minutes)
0
1
2
3
4
5
6
7
8
9
10
Temperature
75
65
57
55
55
55
53
50
47
45
43
(i) Draw a graph of these observations.
(ii) Find out the melting points of the solid object from the following graph.
Answer:
(i)Graph







(ii) 1 Large Square = 80 C0
1 Large Square = 11 Minutes.
Temperature along x-axis.
Time along y-axis.
Result/Conclusion/Finding:
The reading (55C0) at 3, 4, 5 minute indicates are same, so (55C0) is the melting point of the sample.
7. Use the words given to represent the changes taking place in the following processes.
a c
Ice ========Water ======== Steam

b d
Condensation, Melting, Freezing, Boiling.

Answer
Melting Boiling
Ice ============= Water =========== Steam
Freezing Condensation









1 Fill in the blanks;
(i) A homogenous mixture of two substances is called a solution.
(ii) A substance present in relatively lesser amount in a solution is called solute.
(iii)The amount of a solute present in 100 g of a solvent to give a saturated solution at a particular temperature is called solubility.
(iv) A solution whose concentration is known is called standard solution.
2. Which of the following statements are true or false?
(i) There is force of attraction between solute and solvent particles. (T)
(ii) The solubility of an ion is due to its hydration. (T)
(iii)An insoluble solute is present in a super saturated solution. (F)
(iv)Polar solvent s dissolved only polar solutes. (T)
3. Describe with examples the different types of solutions.
Answer: There are nine different types of solution given below with examples.

S/No
Solution
Solute + Solvent
Example
1
Solid in Solid
Alloys (Brass,Nichrome)
2
Solid in Liquid
Brine (Concentrated solution of Table salt)
3
Solid in Gas
Smoke particles in air
4
Liquid in Solid
Absorption of water in chalk
5
Liquid in Liquid
Alcohol in water
6
Liquid in Gas
Water vapours in air
7
Gas in Solid
Hydrogen gas adsorbed on surface of Palladium
8
Gas in Liquid
Carbonated drinks (Pepsi)
9
Gas in Gas
Air

4 Define the followings (i) Solution (ii) Solute (iii) Solvent (iv) solubility (v) Concentration.
Answer:
(i)Solution: It is a homogenous mixture of two or more substances.
Solution = Solute + Solvent
Homogenous means composition is uniform throughout the mixture i-e
one can not demarcate b/w the solute particles and the solvent particles
of a solution.
(ii) Solute: The substance mixed in lesser amount in binary solution is called a solute e.g. table salt if added (two spoons) in a glass of water, the salt here is solute and water is solvent.
(iii) Solvent: The substance mixed in greater amount in binary solution is called a
solvent e.g. Water is a universal solvent b/c it can dissolve different ionic
as well as covalent solutes like NaCl, C6H12O6 etc.
(iv) Solubility: It is defined as Maximum Amount of solute in grams that saturates
100 g of a solvent at a given temperature.
(v) Concentration: It is amount of solute present in specific amount of solvent, more the solute, more will be the concentrated the solution vice versa.
5. Why hydrocarbons such as Petrol, Gas, Grease and Benzene etc.do not dissolve in water?
Answer: Due to their non-polar nature they are not soluble in water.
6. Which one is soluble in water? Kerosene oil, Chloroform, Methanol (CH3OH).
Answer:
Soluble
Not-Soluble
Methanol
Reason: because of presence of OH group
Kerosene oil
Chloroform

7. Why is Magnesium Chloride (MgCl2) soluble in water but Magnesium Hydroxide
(Mg(OH)2) insoluble?
Answer: The force by which Mg (OH)2 is held together is very strong So water cannot split
Mg(OH)2 by the energy released during hydration process. But in case of MgCl2 it
splits into ions easily because the hydration energy is able to split apart Mg++ cation
and Cl-anion and thus both the cation and anion are surrounded by –S partial negative
and +S partial positive poles of water molecules respectively
8. Is it possible to make a saturated solution of Alcohol and water?
Answer: No it is not possible when liquid solute is soluble in liquid solvent in all proportions
9. Is dissolution of hydrogen chloride gas in water a physical change or a chemical reaction?
Answer: it is a physical change because can be reversible in few minutes.
10. What is meant by soloubility? Explain the factors which affect it.
Answer: Solubility:
Solubility of a substance is defined as Maximum Amount of solute in grams
that can saturate 100 g of a solvent at a given temperature.
Factors:
Nature of solute and solvent:
It has a grate impact because we know that like dissolves
like i-e ionic or polar substances can easily be dissolved in water (highly polar compound)
Similarly non-polar substances like grease easily get dissolves in non-polar solvents
like benzene or petrol.
Effect of Temperature:
Temperature has no effect on solubility of some salts like NaCl
and KCl or have negligible effect but opposite to that the dissolution of sugar is
highly effected(Positive on increasing temperature)
The solubility of gas in liquid decreases by increase in temperature.
Effect of Pressure:
Pressure has a very good effect on dissolution of gas like CO2 gas
is dissolved under high pressure in Pepsi bottles which comes out at once with a
fizzy sound or with effervescence on it opening.

11. Calculate the amount of sodium hydroxide required to prepare 500 cm3 of 0.1M
Sodium hydroxide solution.
Answer: Solution:
Mass of Sodium hydroxide NaOH = 1 x 23 + 1 x 16 + 1 x 1 = 40 amu
Volume = 500 cm3
Volume in liters = 500 = 0.50 liter
1000
Molarity of solution = 0.1 M.
We know that Molarity = Number of moles of solute Equation __1
Volume of solution in liters
And Number of moles of solute = Mass in solute grams (Given) Equation __2
Molecular mass/Formula mass
So Molarity = Mass in solute grams x 1
Formula mass Volume of solution in liters
Or Mass in solute grams = Molarity x Formula mass x Volume of solution in liters
Mass in solute grams = 0.1 x 40 x 0.5
Mass in solute grams = 2 grams (Answer)
12. Calculate the number of moles of Sulphuric acid required to prepare 400 cm3 of 6M Sulphuric acid solution.
Answer: Solution:
Number of moles of H2SO4 =?
Volume of solution = 400 cm3
Volume of solution in liters = 400 = 0.40
1000
We know that Molarity = Number of moles of solute
Volume of solution in liters
Or Number of moles of solute = Molarity x Volume of solution in liters
Number of moles of solute = 6 x 0.40
Number of moles of solute = 2.4 (Answer)

13. 100 g of sodium hydroxide are dissolved in water and the volume of the solution is
made 1dm3.Determine the molarity of this solution.
Answer: Solution:
Mass of Sodium hydroxide NaOH = 100 grams
Formula mass = 40 grams
Volume = 1 dm3

We know that Molarity = Mass in solute grams x 1
Formula mass Volume of solution in liters
Or Molarity = 100 x 1
40 1
Molarity = 2.5 (Answer).





1. Fill in blanks.
(i) The flow of electron is called current.
(ii) The vessel in which chemicals produce electricity is called cell
(iii) Cathode is the electrode through which electrons leave the cell .
(iv) The unit of quantity of electricity is coulomb.
(v) The cell in which a chemical reaction takes place at the expense of electrical energy is
called electrolytic cell.
(vi) A chemical reaction in which electrons are lost is called oxidation reaction.
(vii) A substance through which electricity cannot pass is called non-conductor.
(viii) A compound which decomposes into its components when electricity is passed through
it is called electrolyte.
(ix) The electroplating is done for protection and repairing.
2. Label the following sentences as true or false.
(i) All water soluble substances are conductors. (F)
(ii) An electrolyte which completely dissolves in water is always a strong electrolyte.(T)
(iii) Hydrogen is liberated at the anode when acidified water is electrolyzed.(F)
(iv) An ampere is the unit of current strength.(T)
(v) A cathode is a positively charged electrode.(F)
3. Define the followings.
(i) Electrolysis(ii) Electrolyte(iii) Non-Electrolyte(iv) Conductor(v)Ampere(vi)Cell (vii)Electrode
(viii) Coulomb (ix) Ionization
Answer:
(i) Electrolysis: The lysis (Break down/splitting) of an electrolyte into its components i-e positive and negative charged particles due to passage of electric current is called electrolysis.
(ii) Electrolyte: The substance through which electric can pass either it is in molten state or in solution, is called an electrolyte e.g. acid solutions, salts etc.
(iii) Non-Electrolyte: The substance through which electric cannot pass either it is in molten state or in solution, is called non- electrolyte e.g. sugar solution etc
(iv)Conductor: Substances through which current can pass e.g. Iron, Copper, Aluminum etc.
(v) Ampere: It is unit of current. It may be defined as when a charge of one coulomb passes through a conductor in one second that much current is called one Ampere.
(vi)Cell: The container/Vessel in which Redox reactions occur. There are two main kinds of cell.
(a)Electrolytic cell: Works on the expense of external electrical energy.
(b) Voltaic cell: Produce electrical energy by Redox reaction.
(vii)Electrode: The metallic plates or rods through which electric current enters or leaves the cell are called electrodes.
(viii)Coulomb: It is unit of electric charge
Mathematically Coulomb = ampere (A) x time (S)
One coulomb is the amount of electricity produced by current of one ampere if passed through
a conductor for one second.
(ix) Ionization: Process of formation of ions is called ionization Or Splitting of an electrolyte into charge particles or
ions due to passage of electricity is called ionization. Or Electrolyte splits in molten state in aqueous solution or if it
is converted in liquid phase, this process is called ionization.
4. What is the difference between a chemical reaction and an electrochemical reaction?
Answer: Chemical reaction:
In the chemical reaction redox reaction occurs usually in aqueous medium.
Electrochemical reaction:
Transfer of electrons occurs through external circuit e.g. in Voltaic cell.
5. Are water and acetic acid weak electrolytes or strong electrolyte? Explain your answer.
Answer: Both are weak electrolytes
Reason :( Water as a weak electrolyte)
Pure water ionizes up to very negligible extent i-e out of 6x108 molecules
only one molecule is ionized.
Reason :( Acetic acid as a weak electrolyte)
In 2 Molar solution of acetic acid only four out of every thousand molecule
get ionizes while remaining 996 exists as unionized molecules.
6. Differentiate between the followings:
1 Gram equivalent and electrochemical equivalent.
2 Electrolytic dissociation and thermal dissociation
3 Electrolysis and Electrolyte.
4 Cathodes and Anode
Answer:
1 Electrochemical equivalent:
Quantity of substance deposited or liberated when one coulomb of electricity is passed
is through an electrolyte, that much amount is called electrochemical equivalent.
Gramchemical equivalent:
If one Faraday of electricity is passed through an electrolyte, the amount of substance deposited is called Gramchemical equivalent.
2 Electrolytic dissociation:
Dissociation of a substance by passing electricity is called Electrolytic dissociation. Like incase
of electrolysis process.
Thermal dissociation:
If dissociation is occurred due to heat then such dissociation is called Thermal dissociation.
Like dissociation of Calcium Carbonate to give Calcium Oxide and evolution of Carbon dioxide.
Reaction:
CaCO3­ (g) ______ CaO + CO2
3 Electrolysis:
It is a process usually performed on electrolyte for purification or extraction of metals.
Electrolyte:
It is that substance upon which electrolysis is performed, an electrolyte may be strong or poor
(Depends upon its degree of ionization).
4 Cathodes:
The electrode connected with the negative terminal of the battery is called cathode, Reduction occurs here.
Anode:
The electrode connected with the positive terminal of the battery is called anode, Oxidation occurs here.
7. What is the difference in the products obtained when fused sodium chloride and aqueous solution of sodium chloride are electrolyzed? Explain the reasons for this difference.
Answer: We will get caustic soda (NaOH), Hydrogen (H2), Chlorine (Cl2) as product if brine (Concentrated solution of
NaCl) is electrolyzed while we will get only pure sodium (Na) metal and chlorine (Cl2) gas if fused (molten)
table salt is electrolyzed.
Reason:
In the former process caustic soda (NaOH) and Hydrogen (H2) is obtained because of water.
8. What are the factors which control the quantity of the products to be deposited at the electrodes during the process of electrolysis?
Answer: Following three factors are given below.
(i) Quantity of current passed.
(ii) Time interval.
(iii) Charge on the ion, which gets deposited.
9. On what basis ions are arranged in the electrochemical series?
Answer: Ions are arranged in the electrochemical series on the basis of ease of discharge.
10 What are the main objectives of electroplating?
Answer: Three main objectives are given below.
(i) Decoration / Ornamental purpose
(ii) Protection
(iii) Repairing
11. Which of the following pairs react together? Write down chemical equations where applicable.
(i) Zinc + Copper oxide
(ii) Zinc + Iron nitrate
(iii Iron + Magnesium oxide
(iv) Magnesium + copper sulfate
(v) Copper + Lead Nitrate
Answer:
(i) Reaction occurs:
Zn + CuO_____ ZnO + Cu
(ii) Reaction occurs:
Zn + Fe (NO3) ______ Zn (NO3) + Fe
(iii) Reaction does not occur: Because Fe being less reactive, not able to displace magnesium from its oxide.
Fe + MgO ______ No Reaction
(iv) Reaction occurs:
Mg + CuSO4 _______ Mg SO4 + Cu
(v) Reaction does not occur: Because Cu being less reactive, not able to displace Lead (Pb) from its nitrate.
Cu + Pb (NO3)2 ______ No reaction.
12. Why Gold, Silver and Platinum are used for making ornaments?
Answer: Reason:
(i) They look aesthetic/attractive.
(ii) They do not take rust or oxidation.
(iii) They are elastic and can be moulded to any shape.
13. Predict the products obtained by the electrolysis of the followings compounds or solutions.
(i) Dilute solution of Sulphuric acid using inert electrode.
(ii) Fused Lead bromide using inert electrodes
(iii) Aqueous solution of silver nitrate using Silver electrode
Answer:
(i) Ionization of Sulphuric acid occur as
H2So4 (aq) ______ H+ (aq) + HSO4 -1 (aq)
HSO4 -1(aq) ___________ H+(aq) + SO4 -2 (aq)
Ionization of water is given below
2H2O _____ 2 H+ + 2OH-1
At anode: (Oxidation)
2OH-1 ______ 2OH + 2 e
OH + OH or 2OH _____ H2O + O
O + O ________ O 2 (g)
At cathode: (Reduction)
2 H+ + 2 e ______ H 2 (g)
(ii) Ionization of Sulphuric acid occur as
PbBr2 ______ Pb+2 + 2Br -1
At anode: (Oxidation)
2Br -1 _____ Br2 + 2e
At cathode: (Reduction)
Pb+2 + 2e _______ Pb
(iii) Ionization of aqueous Silver nitrate (AnNO­3­) occur as
AgNO3 ===== Ag+ + NO3-1
2H2O _____ 2 H+ + 2OH-1
At anode: (Oxidation)
2OH-1 ______ 2OH + 2 e
OH + OH or 2OH _____ H2O + O
O + O ________ O 2 (g)
At cathode: (Reduction)
Ag+ + e ______ Ag (deposited)
14. What happens when electricity is passed through a solution?
Answer: The mobile ions moves towards their respective electrodes i-e catain to cathode and anion to anode for
reduction and oxidation respectively
15. Classify the following solids as conductors or non-conductors
Aluminium, Sodium Chloride, Urea, Copper Chloride and Platinum.
Answer: Conductors: Aluminium, Platinium
Non-conductors: Sodium Chloride (solid), Copper Chloride (solid), Urea.
16. Describe the silent features of the ionic theory. How does it help in explaining the process?
of electrolysis?
Answer: History: 1887
Scientists: Arrehenius (Swedish)
Silent features of ionic theory are given below:
(i)When electrolytes are fused or dissolved in water, they splits into positive and negative ions. This process is
called ionization.
(ii)The total positive charge is equal to the total negative charge and the solution/sample or the molten mass as a whole
is electrically neutral.
(iii)Metallic ions, ammonium ions and hydrogen ions carry positive charge while non-metallic ions and hydroxide
ions carry negative charge.
(iv)The number of electrical charges present in any ion is equal to the valency of the atom or the radical.
(v) The properties of ions are different from the properties of the related atoms.
(vi) Ions move in all possible directions in fused salts or in aqueous solutions of salts.
(vi) When an electric is passed through an electrolyte, the positive ions are attracted towards the cathode while
negative ions tend to move towards the anode.
Information given by ionic theory:
Practically the same is observed during electrolysis so ionic theory gives us a clear picture of electrolytic process.
17. Explain the Faradays Laws of electrolysis.
Answer: Faradays Laws of electrolysis:
Faradays put forwarded two laws about electrolysis.
Faradays First Law of electrolysis:
Mass of an element deposited or liberated at an electrode during electrolysis is directly proportional to the quantity of current passed through the electrolyte,
Mathematically m & Q (Q=I x t, I=Current, t=Time in seconds)
m & I x t (m=mass ,Z=Electrochemical equivalent)
m = Z x Q
Faradays second Law of electrolysis:
When same quantity of electric current is passed for the same time, through different electrolytes connected
in series, the substances deposited at the electrodes will be in ratio of there chemical equivalents.
17.b Define chemical equivalent.
Answer: Chemical equivalent:
The chemical equivalent of an element is numerically equal to its relative atomic mass in
grams divided by its electrovalency (Valency of the ion)
Faradays second law of electrolysis can also be stated as under.
“The mass of different substances liberated or deposited by the same quantity of electricity
is proportional to the atomic masses divided by the valencies of their ions”
Explanation:
Take three solutions of electrolytes Silver nitrate (AnNO­3­), Copper Sulphate (CuSO4), and
Aluminum Nitrate [Al (NO3)3] in a series, pass some quantity of electricity through for the same time, Now
Ag, Cu and Al metals will collect at the cathode. Their masses will be directly proportional to their equivalent masses.
According to Faraday, If 96,500 Coulombs or one Faraday is passed through these electrolytes
(Stated above), so then we will get Ag 108 , Cu 53.54 , Al 27 Or 108gof Ag ,31.75g of Cu,
1 2 3
9g of Al.
Mathematically.
Equivalent mass. = Atomic mass of element
Valency of element
18. What quantity of copper will be deposited if a current of 2.21Ampere is passed through Copper sulfate solution for three hours and 15 minutes?
Answer: Solution:
Given data:
I = 2.2 Ampere
t = 3 hours and 15 minutes (conversion)
t = 3 x 60 x 60 + 15 x 60 = 11700 seconds.
We know that.
95,000 coulombs of electricity deposits copper = 1 moles or 31.77g
2
So 1 coulombs of electricity will deposits copper = (x) g
By cross multiplication we will get
1 x 31.77 = 96,500 x (x)
31.77 = (x)
96,500
Or (x) = 0.003296= Z=Electrochemical equivalent.
Amount of Copper deposited = Z x I x t
Amount of Copper deposited = 0.003296 x 2.2 x 11700
Amount of Copper deposited = 8.51g (Answer)
19. 0.1978 grams of Copper is obtained on electrolyzing Copper salt solution for five mints using 2 Ampere current. Calculate the electrochemical equivalent of Copper.
Answer: Solution:
Given data:
Amount of Copper deposited = m = 0.1978g
I = 2 Ampere [m = mass deposited]
t = 5 minutes (conversion) [Q= quantity of current passed=Ixt]
t = 5 x 60 = 300 seconds [I=Current in Amperes]
Electrochemical equivalent = Z =? [t = time in seconds]
Z = m
Q
Or Z = m_
I x t
Z = 0.1978
2 X 300
Z = 0.03296 (Answer)
20. What is the difference between an electrolytic cell and a Voltaic cell?
Answer: The main differences between both the cell are given below:
Electrolytic cell
Voltaic cell
Works on supply of external current
Produces current i-e used outside the cell to run electrical toys, appliances.
Redox reaction occurs non-spontaneous (Stops if external support/ Energy is cut off)
Spontaneous redox reaction occurs if external is complete
Used for Electroplating and purifying of metals
Used in cars ,buses as battery for flash lights and to run other electrical appliances
21. Describe the construction and working of Dry cell and a Lead Storage Battery. Give their uses in every
day life.
Answer: Dry cell:
Construction:
It has an external cover of cardboard or a metal, which protects the cell from the environment.
There is a zinc container inside this external cover, which is used as anode. This zinc container
is filled with a moist mixture of ammonium chloride,( NH4Cl),manganese dioxide,(MnO2) and
powdered carbon. A graphite rod, placed at the center of this paste, act as cathode. The cell is
made waterproof using wax, shellac or any other such material.
Reactions (Working):
Zinc is oxidized at the zinc anode.
Zn(s) _________ Zn+2 + 2e-
At graphite cathode,NH4Cl-MnO2 mixture is reduced to form two different products.
2MnO2(S) + 2NH4(aq) + 2e- ______ Mn2O3(s) + 2NH3(aq) + H2O(l)
Ammonia produced at the cathode reacts with Zn2 ions to form [Zn (NH3)4] +2 complex ions.
Lead Storage Battery:
Construction:
It is a common automobile battery, which is also called Lead accumulator. It is usually of
6 or 12 volts. The voltage depends upon the number of cells used. There are several galvanic cells
in the battery ,which are connected in series. Plates like electrodes are used in these cells.
One electrode is of lead (Pb) and the other one is of lead dioxide (PbO2).The electrolyte is
dilute Sulphuric acid. When the battery is fully charged, the Sulphuric acid is 30% by mass .A single
cell provides two volts. For 12 volts 6 cells are connected in series.
Reactions (Working):
Following redox reactions takes place during working of Lead Storage Battery.
H2SO4(aq) ========= 2H+ (aq) + SO4-2 (aq)
At anode:
Pb (aq) + SO4-2 (aq) ======== PbSO4 (S) + 2e-
At cathode:
PbO2 (S) + 4H+ (aq) + SO4-2 (aq) + 2e- ========== PbSO4 (S) + 2H2O(l)
Overall reaction:
Pb (aq) + PbO2 (S) + 4H+ (aq) + SO4-2 (aq) ========= 2PbSO4 (S) + 2H2O(l)
Additional advantage of this battery:
The electrode reactions can be reversed if higher potential than that of the battery is applied from
an external source, also called as recharging process. In this process the external positive potential
is connected with the positive electrode of the battery and the external negative potential is
connected with the negative electrode of the battery. In this way Sulphuric acid, which had
been consumed while the battery was in use, is regenerated.
Uses of Dry cell:
It is used in flash light, portable radio, toys etc.
Uses of Lead Storage Battery:
It is used as battery in all type of vehicles.
Now-a-days widely used in making U.P.S ( urgent power supply) for domestic purposes.