Topic:
Periodic Properties
Question1:
a) Write the name and chemical symbol of the element placed in second row and group 15
of the Periodic Table.
b) Write the name and electronic configuration of the most electronegative
element of the Periodic Table.
c) Name the metalloid of the third period in the Periodic table.
d) State the Modern Periodic Law.
e) Define ionization potential.
Question2:
a) Why does metallic character decrease along a period as we move from left to right?
Give 2 reasons.
b) Why do inert gases have zero values of electron affinity?
c) Why is the electron affinity of lithium higher than that of sodium?
d) Though present in the same period, sodium is highly electropositive, while chlorine is
highly electronegative. Give 2 reasons.
Question 3:
a) Distinguish between electron affinity and electronegativity.
b) Why does atomic size decrease along a period from left to right?
39
K, write the atomic number and atomic mass number. Also calculate the ratio of
19
the number of neutrons to that of protons.
c) For
d) Arrange the elements Si, S, and P in the increasing order of electronegativity and the
elements Na, Mg and Al in the decreasing order of atomic size.
Question 4
Observe the table carefully and answer the questions given below:
Li
Be
B
C
N
O
F
Ne
a) To which period of the Periodic Table does this set of elements belong?
b) Arrange the above elements in the increasing order of electropositive character.
c) Which of the above elements is an alkaline earth metal?
d) Give the name of the element with the highest I.P in this period.
--------------------------Topic: Chemical Bonding
Question 1
Distinguish between the following terms: ( 1 point) :
a) Electrovalency and Covalency :
b) Dissociation and Ionsiation:
c) Covalent bond and Co-ordinate covalent bond:
Question 2:
Draw the electron dot structures for the formation of the following :
a)
c)
e)
Nitrogen
Magnesium chloride
Ammonium ion
g) the cation formed when an acid is dissolved in water.
Question 3:
b) Ammonia
d) Calcium oxide
f) Carbon tetrachloride
Distinguish between ionic compounds and covalent compounds:
a) Based on electrical conductivity
b) Based on solubility:
Question 4:
Give reason/s: Ionic compounds are hard crystalline solids.
Question 5:
A certain period of the Periodic table is given below. The actual symbols of the elements have
been replaced with some alphabets. C does not represent Carbon; H does not represent
hydrogen while F represents fluorine. Observe the table carefully and answer the questions
given below:
Group1
Group 2
Group13
Group14
Group15
Group16
A
B
C
D
E
X
Group17
F
Group18
Y
a) Write the chemical formula of the compound formed between the elements B and X.
b) Which element has the highest Ionisation Potential in this period?
c) What is the valency of the element C?
d) Identify the type of chemical bonding in the compound formed between the elements
D and F.
e)
Draw the electron dot structure for the formation of the compound formed between the
elements A and F.
--------------------------------------------------------------
Topic: Analytical Chemistry
Question 1
Write balanced chemical equations for the following chemical reactions and name the main
product formed:
a) The action of 2-3 drops of sodium hydroxide solution on calcium chloride solution
--------------------------------------------------------------------------------------------------b) The reaction of aluminium with hot caustic soda solution
---------------------------------------------------------------------------------------------------
c) The reaction of ammonium hydroxide with aqueous solution of iron (III) nitrate
------------------------------------------------------------------------------------------------d) The action of hot caustic potash solution on zinc hydroxide
-------------------------------------------------------------------------------------------------e) The reaction of copper nitrate solution with a few drops of ammonia solution initially
followed by excess of the reagent.
_______________________________________________________________________
f) The reaction of lead nitrate solution with few drops of sodium hydroxide solution initially
followed by excess of the reagent.
Question 2
Write down the observation /s for the following chemical reactions:
a) Ammonium hydroxide solution is added dropwise and then in excess to copper sulphate
solution
b) Sodium hydroxide solution is added dropwise and in excess to zinc sulphate solution
---------------------------------------------------------------------------------------------------------------------c) Zinc is reacted with hot caustic potash solution
___________________________________________________________________________
Question 3
Name / State the following:
a) The oxides which can react with acids as well as bases to give salt and water:________
b) An oxide which is yellow in colour when hot and white in colour when cold._________
c) A cation which does not have a metal ion. _____________________
d) The chemical formula of the clear colourless salt solution formed when excess of sodium
hydroxide is added to zinc chloride solution._____________
e) An orange coloured anion ____________________________
----------------------------------------------------------
Question 4 :
Using simple chemical tests and relevant chemical equations, distinguish between the following
pairs of compounds:
i) Calcium nitrate and lead nitrate
ii) Copper (II) chloride and Iron (II) chloride
iii) Zinc nitrate and lead nitrate
______________
Topic: Hydrogen chloride
Question 1:
Give balanced chemical equations for the following:
a) The preparation of hydrogen chloride from rock salt.
b) The action of dil HCl on marble chips.
c) The reaction of lead (IV) oxide with conc. HCl
d)
The reaction of sodium thiosulphate with dil.HCl
Question2:
a) Give a chemical test to detect the presence of hydrogen chloride gas
b) Give a chemical test to detect the presence of chloride ions in a salt. Give relevant equations and
observations.
c) Mention two properties of hydrogen chloride gas demonstrated by the Fountain experiment.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------d) What are the advantages of the special funnel arrangement used to dissolve HCl gas in water?
______________________________________________________________________________
e) Why is it important to maintain temperatures less than 2000C in the preparation of hydrogen
chloride gas from sodium chloride?
______________________________________________________________________________
Question 3:
a) Why does hydrogen chloride gas fume in moist air?
b) Name the drying agent used to dry hydrogen chloride gas. Why is this substance chosen as the
drying agent for HCl? Why is quick lime not used to dry HCl gas?
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
________________________________________________________________________________
(c) Mention the mode of collection of HCl gas during its preparation from NaCl. State the reason(s)
for the same.
________________________________________________________________________________
__________________________________________________________________________
d)
Dry hydrogen chloride gas is neutral to litmus while an aqueous solution of hydrogen chloride
turns blue litmus paper red. State the reason(s).
_____________________________________________________________________________________
___________________________________________________________________________________
Question 4:
Write the observation/s for the following chemical reactions:
a) A few drops of methyl orange are added to dilute hydrochloric acid.
____________________________________________________________________________
b) Sodium sulphite is treated with dil.HCl and heated.
_______________________________________________________________________________
_____________________________________________________________________________
c) Dilute Hydrochloric acid is heated with iron (II) sulphide.
_______________________________________________________________________________
_______________________________________________________________________________
d) An aqueous solution of lead nitrate is added to dil.HCl.
_______________________________________________________________________________
Question 5
Using a chemical test, how will you distinguish between Manganese dioxide and Copper
( II ) oxide? (two observations ). Give relevant chemical equations.
_______________________________________
Topic: Ammonia
Question 1:
Write balanced chemical equations for the following chemical reactions:
a) The industrial process of manufacture of ammonia
_____________________________________________________________________
b) The laboratory preparation of ammonia from sal ammoniac and slaked lime
a) The action of water on calcium nitride and aluminium nitride respectively
b) The catalytic oxidation of ammonia
c)
The reaction of ammonia with heated copper (II) oxide
d) The reaction of excess ammonia with chlorine
Question 2:
a) Give two colour tests to detect the presence of ammonia, giving relevant
observation/s:
a. Write the properties of ammonia demonstrated by the fountain experiment.
-----------------------------------------------------------------------------------------------------b. Name the apparatus used to dissolve ammonia gas in water.
-----------------------------------------------------------------------------------------------------c. During the preparation of ammonia in the laboratory, how is it confirmed that a glass
jar is full of ammonia?
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------d. Why are optimum temperatures employed in Haber’s process?
-----------------------------------------------------------------------------------------------------e. Why is dry ammonia gas is neutral to dry litmus?
___________________________________________________________________
__________________________________________________________________
Question 3:
Give relevant observation/s for the following chemical reaction/s:
a) Ammonia is passed over lead (II) oxide.
b) Ammonia is burnt in oxygen
c) Ammonia is reacted with excess chlorine
d) A few drops of methyl orange are added to ammonium hydroxide
Topic : Nitric acid
Answer the following questions:
Question 1:
Write balanced chemical equations for the following:
a) Preparation of nitric acid from nitre
--------------------------------------------------------------------------------------------------------b) Reaction of manganese with very dilute, cold nitric acid
-------------------------------------------------------------------------------------------------------c) Action of hot concentrated nitric acid on sulphur
-------------------------------------------------------------------------------------------------------d) Reaction between baking soda and dilute nitric acid
Question 2:
Give your observation/s for the following:
a) Concentrated nitric acid is poured over copper turnings.
--------------------------------------------------------------------------------------------------------b) Sodium sulphite is treated with dilute nitric acid
-------------------------------------------------------------------------------------------------------c) Hot concentrated nitric acid is added to saw dust kept in a porcelain dish.
-------------------------------------------------------------------------------------------------------d) A few drops of methyl orange are added to nitric acid
Question 3
Write the equations involved in the industrial preparation of nitric acid (Ostwald’s process)
______________________________________________________________________________
Question 4:
Name the following:
a) The compound which constitutes the brown ring in the chemical test used for the
detection of nitrate radical. -------------------------------------------------------------b) The yellow coloured compound formed when nitric acid comes in contact with our skin
------------------------------------------------c) The process of conversion of atmospheric nitrogen into useful nitrates which can be
used by plants.
-------------------------------------------------Question 5:
Give reason/s for the following:
a) An all glass apparatus is used in the laboratory preparation of nitric acid from nitre.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------b) Nitric acid prepared in the laboratory is yellow in colour..
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Topic: Sulphuric acid
Answer the following questions:
Question 1:
Write balanced chemical equations for the following:
a) Catalytic oxidation of sulphur dioxide in Contact process
--------------------------------------------------------------------------------------------------------b) Reaction of copper with conc. sulphuric acid
-------------------------------------------------------------------------------------------------------c) Action of dilute sulphuric acid on washing soda
-------------------------------------------------------------------------------------------------------d) Reaction of conc. sulphuric acid with copper sulphate pentahydrate crystals
---------------------------------------------------------------------------------------------------------Question 2:
Give your observation/s for the following:
a) Concentrated sulphuric acid is added to glucose
--------------------------------------------------------------------------------------------------------b) Sodium sulphite is treated with dilute sulphuric acid
-------------------------------------------------------------------------------------------------------c) A few drops of alkaline phenolphthalein are added to dilute sulphuric acid
-------------------------------------------------------------------------------------------------------d) Zinc granules are added to dilute sulphuric acid
Question 3:
Give reason/s for the following:
a) Sulphur trioxide is not absorbed in water during the industrial preparation of
sulphuric acid
------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------b) An optimum temperature is used for the oxidation of SO2 to SO3 during Contact
process.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------________________________________________________________________________
c) When concentrated sulphuric acid comes in contact with our skin , charring of our
skin occurs
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
d) Vanadium pentoxide is preferred to platinised asbestos as a catalyst in Contact
process
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Question 4
Write the role of sulphuric acids in the following chemical reactions. Also give the
balanced chemical equations for the chemical reactions.
a) reaction zinc with dil sulphuric acid:
b) reaction zinc with conc. sulphuric acid:
c) action of conc. sulphuric acid on blue vitriol
d) reaction of conc. sulphuric acid with nitre
e) reaction of sodium sulphide with dilute sulphuric acid
Question 5
Write the balanced chemical equations for the following chemical reactions
Concentrated sulphuric acid is poured over canesugar.
_____________________
Topic: Acids, Bases and Salts
Question 1: Give balanced chemical equations for the following:
i) Preparation of Lead (II) chloride from Lead (II) oxide (2 steps)
____________________________________________________________
------------------------------------------------------------------------------------------iii Neutralization of iron (III) hydroxide using dilute nitric acid
-----------------------------------------------------------------------------------------v) The decomposition of ammonium carbonate using dilute sulphuric acid
----------------------------------------------------------------------------------------Question 2: Write the observation/s for the following chemical reactions:
i) Copper oxide is treated with dilute sulphuric acid
----------------------------------------------------------------------------------------ii) Washing soda crystals are left exposed to air for a few days.
__________________________________________________________
iii) aqueous solutions of calcium chloride and sodium carbonate are mixed
together and stirred
-------------------------------------------------------------------------------------Question 3. Classify the following as acidic, basic or normal salts. Support your answer
with the definition of the type of salt:
i)
NaHSO4
ii)
Zn (OH)Cl
iii)
Na3PO4
Question 4. Define the following:
i)
Water of crystallization:
___________________________________________________________________
________________________________________________________________________
ii)
Deliquescence:
______________________________________________________________
________________________________________________________________________
Question 5: Complete the following table:
Name of the salt
Blue vitriol
Glauber’s salt
Name of the method
of preparation
i)
Equation
ii) Decomposition of
carbonate
ii)
i)
NaOH+
i)
Mistakes to be
avoided
Cu + H2SO4
Na + H2SO4
OR
Na2CO3 +
Zinc sulphate
ii) Decomposition of
carbonate /
bicarbonate
i)
OR
ii)
Iron (II)sulphate
Iron (III) chloride
Lead sulphate
from Lead
carbonate
2 steps:
Pb + H2SO4
i)
i)
ii)
ii)
Question 6. Classify the following as hygroscopic, deliquescent or efflorescent:
Calcium oxide, fused calcium chloride, conc,. sulphuric acid, Galuber’s salt, blue vitriol, silica
gel , phosphorus pentoxide.
Hygroscopic:
Deliquescent :
Efflorescent:
________________________________________________________
Topic:
Electrolysis
Question1
Write the electrode reactions for the following:
i)
Electrolysis of acidified water using platinum electrodes
Cathode:-------------------------------
ii)
Anode:----------------------------------------------
Electrolysis of fused lead bromide using graphite electrodes
Cathode:------------------------------iii)
Electrolysis of fused NaCl using graphite electrodes
Cathode:-------------------------------
iv)
Anode:--------------------………….
Anode:------------------------------------------------
Electrolysis of aqueous copper sulphate using copper electrodes
Cathode:-------------------------------
Anode:-----------------------------------------------
Question 2
Distinguish between the following: (any two points):
i)
cathode and anode
ii)
strong electrolyte and weak electrolyte
Question 3:
Define the following:
i)
Electrolysis: -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
ii)
Electroplating: --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Question 4: Give your observation/s for the following ( at both the electrodes and in the
electrolyte, if any) :
i)
Copper sulphate solution is electrolysed using copper electrodes.
ii)
Fused lead bromide is electrolysed using graphite electrodes.
Question 5: Give reason/s for the following:
i)
Dilute sulphuric acid is added to distilled water before subjecting it to electrolysis
_____________________________________________________________________
ii) Sodium argentocyanide solution is preferred to silver nitrate solution as the electrolyte
in the electroplating of silver.
________________________________________________________________________
_______________________________________________________________________
Question 6: Name the following:
i)
The cathode in the electroplating of an iron nail with nickel: ------------------------ii)
The anode in the electroplating of an article with silver:
-----------------------------
iii)
The cathode in the electrorefining of copper: --------------------------------------------
iv)
The electrolyte used in the electrorefining of copper: ----------------------------------
Topic: Mole Concept and Stoichiometry
Set 1: Problems based on Gay Lussac’s Law:
1. Nitrogen and hydrogen react to give ammonia. Calculate the volume of ammonia formed
when nitrogen reacts with 9 litres of hydrogen, all volumes being measured at S.T.P.
Ans: [ 6 lit of ammonia)
2. 250 cm3 of carbon monoxide and 100 cm3 of oxygen are ignited together. Calculate the
composition of the resulting mixture.
Ans: [ 50 cm3 of carbon monoxide , 200 cm3 carbon dioxide, 0 cm3 oxygen]
3. What volume of oxygen would be required to burn completely 300 ml of
ethylene (C2H4) ? Also determine the volume of carbondioxide formed?
(Ans: 900 ml oxygen, 600 ml carbondioxide)
4. 2500 cc of oxygen was burnt with 600 cc of ethane (C2H6). Calculate the volume of
unused oxygen and the volume of carbon dioxide formed.
Ans: [ unused oxygen = 400 cc, volume of carbon dioxide = 1200 cc)
5. 100 cc each of water gas and oxygen are ignited and the resulting gases cooled to room
temperature. Calculate the composition of the resulting mixture. (Water gas contains CO
and H2 in equal ratio)
Ans: [ 50cc unused oxygen, 50 cc of carbondioxide
6. LPG stands for Liquified Petroleum gas. A certain variety consists of 60% propane and
40% butane.. If 10 litres of this mixture is burnt, calculate the volume of carbon dioxide
added to the atmosphere. The combustion reactions are given as follows:
C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)
2C4H10(g) + 13O2(g) → 8CO2(g) + 10H2O(g)
[Ans: 18 + 16 =34 lit carbon dioxide)
7. On igniting a mixture of acetylene and oxygen, 200 cm3 of CO2 is collected at S.T.P.
Calculate the volume of acetylene and oxygen in the original mixture.
[Ans; 100 cm3 acetylene, 250 cm3oxygen]
8. Ethane burns in air forming carbon dioxide and water vapour. Calculate the volume of air
required to burn 100 cm3 ethane. Assume air contains 20% oxygen.
[Ans; 1750 cm3]
9. 100 ml of ethylene is burnt in just sufficient air ( containing 20% oxygen) as per the
equation C2H4 + 3O2 → 2CO2 + 2H2O(g). Calculate the resultant mixture
composition at 1000C and constant pressure.
Ans: 1200 ml nitrogen , carbon dioxide = 200 ml , water vapour = 200 ml,
ethylene and oxygen= 0 ml]
10. 67.2 lit of hydrogen combines with 44.8 lit of nitrogen to form ammonia under specific
conditions:
N2 (g) + 3H2 (g) → 2NH3(g)
Calculate the volume of ammonia produced. What is the other substance, if any , that
remains in the resultant mixture?
Ans: 44.8 lit of ammonia is produced, 22.4 lit of nitrogen remains
11. Calculate the volume of oxygen required for the complete combustion of 8.8 g of C3H8
ie.,propane. ( atomic mass of C=12, H=1, O=16)
C3H8 + 5O2 → 3CO2 + 4H2O(g).
Ans: 22.4 dm3 of oxygen
Set 2: Problems based on Avogadro’s Law:
1. Three gases A, B and C are maintained under similar conditions of temperature and
pressure. If 200 ml of a gas A contains ‘X’ molecules, how many molecules will be
present in a) 100 ml of gas B b) 50 ml of gas ‘C’. ( Answer in terms of X)
Ans: X / 2 molecules of B
b) X / 4 molecules of C
2. Three gases namely CO2, SO2 and H2 contain the same number of molecules ‘X’. If
CO2 occupies ‘Y’ litres, state the volume occupied by a) X molecules of SO2
b) 2X molecules of H2
Ans: a) Y litres of CO2
b) 2Y litres of H2
3. The volumes of gases A, B and C are in the ratio 1 : 2: 3 under similar conditions of
temperature and pressure. a) Which gas contains the maximum number of molecules?
b) What will happen to the volume of the gas A if the number of molecules is tripled ,
provided the temperature and pressure of A are kept constant. c) If volume of A is
11.2 litres at S. T.P, calculate the number of molecules of the gas B at S.T.P..
Ans: a) Gas C
b) Tripled
c) 6.023 × 1023 molecules
Set 3: Problems based on Vapour density and Molecular weight:
1. Calculate the atomicity of a gas [at. wt. 35.5 ] whose vapour density is equal to its relative
atomic mass.
Ans: 2
2. A gas cylinder of capacity 40 dm3 is filled with gas X , the mass of which is 20 g. When
the cylinder is filled with hydrogen gas at the same temperature and pressure, the mass of
hydrogen is 4 g. Determine the vapour density and relative molecular mass of the gas X.
Ans: V.D = 5, relative molecular mass = 10.
3. A gas cylinder holds 70 g of gas X. The same cylinder when filled with hydrogen holds
7.0 g of hydrogen under the same conditions of temperature and pressure. Determine the
gram molecular weight of the gas X.
Ans: 20 g
4. 500 ml of a gas X at S.T.P weighs 0.50 g. Calculate the vapour density and molecular
weight of the gas . Given that 1 litre of hydrogen at S.T.P weighs 0.09g.
Ans: 11.1, 22.2 g
Set 4: Problems based on moles , RMM , GMV and Avogadro number:
1. Calculate the number of moles ( gram molecules) in a) 8 grams oxygen b) 90g water
c) 1.6 grams helium
d) 2.2 grams CO2. Given the atomic weight of H=1, O= 16,
C= 12, He = 4 )
Ans: a) 0.25
b) 5 c) 0.4 d) 0.05
2. Calculate the number of molecules in a) 7 grams of nitrogen b) 32 grams of methane
c) 5.85 g sodium chloride. Given at wt of Na = 23, Cl = 35.5, N= 14, C=12, H=1.
Ans: a) 0.25 × 6.023 × 1023 b) 2.0 × 6.023 × 1023 c) 0.1 × 6.023 × 1023
3. Calculate the number of molecules and atoms in a) 0.25 moles of chlorine
b) 196 g of sulphuric acid. At wt of Cl=35.5, mol.wt of sulphuric acid =98]
Ans: [ a) 0.25 × 6.023 × 1023 molecules, 0.5 × 6.023 × 1023 atoms of chlorine
b) 2× 6.023 × 1023 molecules, 14× 6.023 × 1023 atoms of sulphuric acid]
4. Calculate the weight ( in grams) of a) 5.5 moles of hydrogen b) 2.5 moles of CO
c) 1.5 × 6.023 × 1023 molecules of water d) 3.0115 × 1023 molecules of oxygen
e) 6.023 × 1022 molecules of calcium carbonate. Given atomic weight of H=1, C=12,
O=16, Ca= 40, S= 32
Ans: a) 11.0 g hydrogen b) 70 grams CO c) 27 g water
d) 16 grams oxygen
e) 10 grams calcium carbonate
5. Calculate the a) number of gram molecules b) number of gram atoms in 35.5 grams
chlorine. Atomic wt of Cl = 35.5
Ans: a) 0.5
b) 1. 0
6. Calculate the number of moles of chloride ions and calcium ions which will be obtained
from 222 grams of calcium chloride. [ Ca= 40, Cl= 35.5]
Ans: 2 moles of calcium ions and 4 moles of chloride ions]
7. Calculate the volume at S.T.P of a) 1.5 moles of hydrogen b) 3.2 grams SO2
c) 6.023 × 1022 molecules of ethylene. At. wt of S=32, O=16, C=12, H=1.
Ans: a) 33.6 dm3
b) 0.05 × 22.4 = 1.12 dm3 c) 2.24 dm3
8. Calculate a) the mass of oxygen gas which occupies a volume of 11.2 dm3 at S.T.P.
b) the number of moles present in 5.6 litres at S.T.P of hydrogen
c) the number of molecules present in 2.24 lit of nitrogen .
Ans: a) 16 g b) 0.25 moles c) 6.023 × 1022 molecules of nitrogen
9. 50 grams of hydrogen , oxygen and sulphur dioxide are taken separately in three different
cylinders P, Q and R.
a) Which cylinder contains the highest number of moles of the gas?
b) Which cylinder contains the least number of gas molecules? [At wt O=16, H=1, S=32].
Ans: a) P b) R
10. Calculate the atomicity of a gas ‘X’ if 1 g of ‘X occupies 11,200 cc at S.T.P . Given that
atomic weight of ‘X’ =1.
Ans: Atomicity =2.
11. Calculate the mass of 1022 atoms of sulphur . Given atomic weight of sulphur = 32 and
Avogadro number = 6 × 1023
Ans: 0.53 grams
12. Calculate the relative molecular mass and vapour density of benzene (C6H6) if 390 grams
of the liquid on vaporization has a volume of 112 litres at S. T.P.
Ans: R.M.M = 78, V.D = 39
13. A gas occupies a volume of 100 cc at S.T.P and weighs 0.5 grams . Find its RMM.
Ans: 112.
14. The mass of 5.6 dm3 of a certain gas at S.T.P is 12.0g. Calculate the relative molecular
mass of the gas.
Ans: 48
-------------------------------------------------------------------------------------------------------------
Stoichiometry
Set 5: Problems based on percentage composition
1. Calculate the percentage by weight of a) calcium in calcium carbonate b) oxygen in
hydrogen peroxide c) potassium in potassium dichromate [H=1, O=16, Ca= 40, C=12,K=39.
Cr=52]
Ans: a) 40%,
b) 94.11%
c) 26.53%
2. Calculate the percentage of water of crystallization in Glauber’s salt (Na2SO4.10H2O).
[ Na =23, S=32, O=16, H=1]
Ans: 55.90%
3. What is the mass of nitrogen in 1000 kg of urea whose molecular formula is CO(NH2)2?
[ C=12, H=1, N=14, O=16]
Ans: 466 kg.
4.
Calculate the mass of nitrogen supplied to the soil by 5kg of urea ( molecular formula is
CO(NH2)2 ). [ C=12, H=1, N=14, O=16]
Ans: 2333.3 g
5.
Which is a better fertilizer : Urea or ammonium phosphate? [N=14, C=12, H=1, O=16,
P =31]
Ans: Urea as it has a higher percentage of nitrogen ( N= 46.67% as compared to 28.19% in
ammonium phosphate)
6.
Calculate the percentage of pure aluminium in 10 kg of aluminium oxide (Al2O3) of 90%
purity. [ Al=27, O=16]
Ans: 47.64%
7. Hydrated Calcium sulphate [CaSO4.xH2O] contains 21% water of crystallization. Calculate
the number of molecules of water of crystallization. ie. ‘x’ in the hydrated salt. [Ca= 40,
S= 32, H=1, O=16]
Ans: CaSO4.2H2O
8. Calculate the number of molecules of water of crystallization in copper sulphate crystals, if
10g of hydrated copper sulphate crystals gives 6.4g of anhydrous copper sulphate on heating.
[Cu=64, s= 32, O=16]
Ans: 5 molecules
Set 6: Calculation of Empirical formula and Molecular formula of compounds:
1. Calculate the molecular formula of a compound whose empirical formula is CH2O and
vapour density is 90.
Ans: C6H12O6
2. Write the empirical formula of a) benzene (C6H6) b) Octane ( C8H18)
Ans: a) CH
b) C4H9
3. A compound has C= 57.82%, O = 38.58% and the rest hydrogen. Its vapour density is 83.
Determine its empirical formula and molecular formula.[C=12, H=1, O=16]
Ans: C4H3O2, C8H6O4
4. A metal ‘M’ forms a volatile chloride containing 65.5% chlorine. If the density of the
chloride relative to hydrogen is 162.5, find the molecular formula of the chloride.
[ M=56, Cl =35.5 ]
Ans: molecular formula= M2Cl6
5. A compound has the following percentage composition by mass : C= 14.4%, H=1.2% and
Cl=84.5%. Determine the empirical formula of the compound. The relative molecular mass
of the compound is 168. Determine the molecular formula of the compound.[ C=12, H=1,
Cl=35.5].
Ans: CHCl2, C2H2Cl4
6. A compound has the following percentage composition: Zn=22.65%, S=11.15%,
O= 61.32% and H= 4.88%. Its relative molecular mass is 287. Calculate its molecular
formula assuming that all the hydrogen atoms in the compound are present as water of
crystallization in combination with oxygen.[ Zn=65, S= 32, O=16, H=1]
Ans: ZnSO4.7H2O
Set 7:
Problems on Chemical Equations
1. Determine the volume of hydrogen gas which will be obtained at S.T.P by the action of
3.275 g of zinc with excess dilute hydrochloric acid. [Zn= 65.5]
Ans: 1.12 dm3
2. What will be the volume of oxygen obtained at S.T.P by the decomposition of 61.25g
potassium chlorate (KClO3)? The equation for the decomposition of potassium chlorate is
2KClO3 → 2KCl + 3O2↑
[K=39, Cl=35.5, O=16]
Ans: 16.8 dm3
3. From the equation, 3Cu + 8HNO3 → 3Cu(NO3)2 + 4H2O + 2NO↑. Calculate
a) The mass of copper needed to react with 12.6 grams of nitric acid.
b) The volume of nitric oxide collected at the same time at S. T.P.
[Cu=63, H=1, O=16, N=14]
Ans:
a) 4.8g
b) 1.12 dm3
4. Calculate the weight of potassium nitrate which should be heated to produce 5600c.c of
oxygen gas at S.T.P. [K=39, O=16, N=14].
2KNO3 → 2KNO2 + O2↑.
Ans: 50.50 g
5. A sample of ammonium nitrate yields 8.96 litres of steam at S.T.P.
NH4NO3 → N2O ↑ + 2H2O↑.
a) What volume of nitrous oxide is produced at the same time as 8.96 litres of steam?
b) What mass of ammonium nitrate should be heated to produce 8.96 litres of steam?
[relative molecular mass of ammonium nitrate is 80]
Ans: 4.48 litres, 16 g]
6. P + 5HNO3 → H3PO4 + H2O + 5NO2↑.
a) What mass of phosphoric acid can be prepared from 6.2g of phosphorus?
b) What mass of nitric acid will be consumed at the same time?
c) What would be the volume of steam produced at S.T.P at the same time?
[H=1, N=14, O=16, P=31]
Ans: a) 19.6g b) 63g
c) 4.48 lit
Topic:
Organic Chemistry
Set I – Nomenclature
1. CH3 –CH2 –CH2 –CH3
IUPAC name:
Common name:
Note:
2. CH3 –
CH3
│
CH –CH3
IUPAC name:
Common name:
Note:
3. CH3 –CH2 –CH2 – CH2 –CH3
IUPAC name:
Common name:
4.
CH3
│
CH3 – CH2–CH –CH3
IUPAC name:
Common name:
Note:
5.
CH3
│
CH3 –C–CH3
│
CH3
Note:
IUPAC name:
Common name:
C2H5
│
6. CH3 –CH2–CH – CH3
Note:
CH3
│
7. CH3 – CH2 C –CH3
│
CH3
OH
│
8. CH3 – CH2–CH –CH3
IUPAC name:
IUPAC name:
IUPAC name:
Note:
CH3 OH
│ │
9. CH3 – CH–CH –CH3
Note:
CH3 OH
│ │
10. CH3 – CH–CH –CH3
Note:
C2H5
OH
│
│
11. CH3 – CH–CH2-CH –CH3
Note:
IUPAC name:
IUPAC name:
IUPAC name:
Br
Cl
│
│
12. CH3 – CH–CH2 – CH- CH3
Note:
IUPAC name:
13. CH3 – CH2 – CH - CH- CH2 CH2 CH3
│
│
CH3 C2H5
IUPAC name:
Note:
CH3
Cl
│
│
14. CH3 – CH–CH2 – CH - CH3
IUPAC name:
Note:
Cl
│
15. CH3 CHCH=CH2
IUPAC name:
Note:
CH3
│
16. CH3 –CH2 –C =CH2
IUPAC name:
Note:
17. CH3 CH2CHBr2
Note:
IUPAC name:
CH3
│
18. CH3–C -Cl
│
CH3
IUPAC name:
Note:
19. CH3 –C = C-CH3
│ │
Br C2H5
Note:
CH3
│
20. CH3 –C  C-CH2 –CH –CH3
Br Br
│ │
21. CH3 – C –C-CH3
│ │
Br Br
22. C2H5 CH2 CH CH2OH
│
CH3
CH3 H
│
│
23. CH3- C - C -OH
│ │
CH3 H
24. C2HCl5
IUPAC name:
IUPAC name:
IUPAC name:
IUPAC name:
IUPAC name:
IUPAC name:
Cl Cl
│ │
25. H-C =C –H
IUPAC name:
26. CH2-CH2
27. CH3 CH2 Br
OH OH IUPAC name:
29. CH3 –C  C- CH –CH3
IUPAC name:
name:
IUPAC name:
30. CH3CH2 CH2 CHO
IUPAC name:
28. CH2Cl2
IUPAC name:
31. HCOOH
IUPAC
name:
Set II – Writing Condensed and Branched Structural formula
S.No.
Name of the compound
1.
Pentane
2.
2,2 –dimethyl propane
3.
2-methyl but-2-ene
4.
4-methyl-pent-1-yne
5.
3-methyl pentan-2-ol
6.
1,2 -dibromoethene
7.
2-methyl butanal
8.
2-chloro propanoic acid
9.
Acetone
10.
Acetaldehyde
Condensed
structural formula
Branched structural
formula
11.
Formic acid
12.
Diethyl ether
13.
Ethyl acetate
14.
Ethyl bromide
Set III – Chart of various Homologous Series
Homologous Series: Alkanes or Paraffins;
Molecular
formula
Condensed
structural formula
Gen.formula:
Branched structural formula
Root +
word
Functional Gp :
Sec = IUPAC
suffix
name
Common
Or Trivial
name
n=1
n=2
n=3
n=4
n=5
Homologous Series: Alkenes or Olefins ;
Molecular
formula
n=2
n=3
n=4
Condensed
structural formula
Gen.formula:
Branched structural formula
Root +
word
Functional Gp :
Sec = IUPAC
suffix
name
Common
Or Trivial
name
Homologous Series: Alkynes ;
Molecular
formula
Condensed
structural formula
Gen.formula:
Branched structural formula
;
Functional Group :
Root +
word
Sec = IUPAC
suffix
name
Common
Or Trivial
name
n=2
n=3
n=4
Homologous Series: Alcohols ;
Molecular
formula
n=1
n=2
n=3
n=4
Condensed
structural formula
Gen.formula:
Branched structural formula
;
Functional Group :
Root +
word
Sec = IUPAC
suffix
name
Common
Or Trivial
name
Homologous Series: Aldehydes ;
Molecular
formula
Condensed
structural formula
Gen.formula:
Branched structural formula
;
Root +
word
Functional Group :
Sec = IUPAC
suffix
name
Common
Or Trivial
name
n=1
n=2
n=3
Homologous Series: Ketones ;
Molecular
formula
Condensed
structural formula
Gen.formula:
Branched structural formula
;
Root +
word
Functional Group
Sec = IUPAC
suffix
name
:
Common
Or Trivial
name
n=3
n=4
Homologous Series: Carboxylic acids ;
Molecular
formula
n=1
n=2
n=3
Condensed
structural formula
Gen.formula:
Branched structural formula
Root +
word
Functional Gp :
Sec = IUPAC
suffix
name
Common
Or Trivial
name
Homologous Series: Carboxylic Esters ;
Molecular
formula
Condensed
structural formula
Branched structural formula
Functional Group :
Root +
word
Sec = IUPAC
suffix
name
Common
Or Trivial
name
n=2
n=3
n=5
Homologous Series: Ethers ;
Molecular
formula
Condensed
structural formula
General Formula
Branched structural formula
Functional Gp ::
Root +
word
Sec = IUPAC
suffix
name
Common
Or Trivial
name
n=2
n=3
Homologous Series: Alkyl halides ;
Molecular
formula
n=1
n=2
Condensed
structural formula
Gen. Formula:
Branched structural formula
;
Root +
word
F.G
: Halo ( -Cl, -Br, -I, -F)
Sec = IUPAC
suffix
name
Common
Or Trivial
name
Set IV – Isomerism
Write the branched structural formulae of the isomers of the compounds with the given
molecular formulae. Write their IUPAC and Common names( wherever applicable):
1. C4H10
2. C5H12
3. C4H8
4. C4H6
Pawar Public School, Bhandup
Chemistry worksheet
1.
Topic: Alkanes, Alkenes and Alkynes
Write the structural formula ,the IUPAC and Common names of the isomers of the
compounds represented by the following molecular formulae:
a) C5H12
Structural formula: i)
ii)
iii)
IUPAC name :
IUPAC name :
IUPAC name :
Common name:
Common name:
Common name:
b) Write the structural formula and the IUPAC name of :
i)
a chain isomer of n hexane
ii) a position isomer of 1- pentyne
c) Draw the electron dot structures of
Ethane
Ethylene
2) Give balanced chemical equations for the preparation of :
i)
Ethane from sodium propionate
ii)
Methane from methyl iodide
Acetylene
iii)
Ethane from Iodomethane
3) Write the balanced chemical equations with the necessary conditions for the 4 steps
involved in the photochlorination of methane. Give the IUPAC names of the products formed
in each stage.
_____________________________________________________________________
Overall reaction:
4) Write the balanced chemical equations for the stepwise oxidation of:
i)
Ethane using acidified potassium dichromate
ii)
Methane using heated copper as catalyst
iii)
5.
6.
Ethane using heated Molybdenum oxide catalyst
Write balanced chemical equations for the following:
i)
the complete combustion of ethane
ii)
the incomplete combustion of methane
iii)
the pyrolysis of methane
iv)
the pyrolysis of ethane
How will you prepare ethylene from: ( Give balanced equations with conditions; no
description needed) :
i)
Ethanol
ii)
Bromoethane:
7. How will you bring about the following conversions: ( only equations) :
i)
Ethene to ethane
ii)
Ethene to 1,2 – dibromoethane
iii)
Ethylene to ethyl bromide
iv)
Ethyl bromide to ethylene
v)
Ethene to ethylene glycol
8. Write balanced chemical equations for the following conversions:
i)
Calcium carbide to ethyne
ii)
1, 2- dibromoethane to ethyne
iii)
Ethyne to ethane
iv)
Ethyne to 1,1,2,2 – tetrabromoethane
9. Write your observation(s) for the following chemical reactions:
i)
Ethylene is passed into bromine in carbon tetrachloride
ii)
Acetylene is passed into ammoniacal cuprous chloride solution
iii)
Acetylene is passed into ammoniacal silver nitrate solution
iv)
Ethene is passed into cold alkaline solution of potassium permanganate
10. Give a chemical test to distinguish between the following pairs of compounds:
i)
Ethane and Ethene
ii)
Ethene and Ethyne
11. Write the structural formulae and the IUPAC name of the 2 isomers represented by the
formula C3H7OH.
12. Write the structural formulae and the IUPAC name of the 4 isomers represented by the
formula C4H9OH.
13. Write balanced chemical equations for the following:
i)
The action of aqueous KOH on bromoethane
ii)
The action of alcoholic KOH on bromoethane
iii)
The complete combustion of ethanol
iv)
The complete oxidation of ethanol using acidified potassium dichromate ( 2 steps)
v)
The dehydration of ethyl alcohol
vi)
The reaction of ethanol with sodium ( write observation also)
vii)
The reaction of ethanol with acetic acid and conc sulphuric acid ( write observation
also)
14. What is meant by the terms ‘Denatured alcohol’ and ‘Methylated spirit’?
15. What is meant by esterification? Explain with an example . Mention the role played by
conc. Sulphuric acid.
16.
Give a chemical test in which
i)
An alcohol resembles a carboxylic acid
ii)
An alcohol differs from a carboxylic acid.
17. Write balanced chemical equations for the following :
18.
i)
Preparation of ethanoic acid from ethanol ( 2 steps)
ii)
Reaction of ethanoic acid with calcium
What is meant by ‘glacial acetic acid’?
19. Write two main uses each of methane, ethane, ethane and ethyne.
Methane:
Ethane:
Ethene:
Ethyne:
20. Write four important uses of
i) ethyl alcohol
_______________________
ii) acetic acid.
METALLURGY - I
I.
Group
No.
1 or IA
2 or
IIA
Position of Metals in the Periodic Table
Type of
Elements
Alkali
metals
Alkaline
earth
metals
Elements
Li, Na, K,
Rb, Cs, Fr
Be, Mg,
Ca, Sr,
Ba, Ra
Property

Light & soft metals


Low melting
points


3 to 12 Transition
metals
Fe , Zn,
Cu, Ag


13 to
16
Post
transition
elements
Al
Reason

Highly
electropositive &
reactive and
strong reducing
agents
Heavy & hard
metals


High melting
points

Not highly
electropositive

Weakly
electropositive


Have large atomic size,
hence low density.
Forces binding the atoms
are weak.
Have low ionization
potentials due to large
atomic size. So valence
electrons can be easily
removed from the
outermost shell.
Have small atomic size,
hence high density.
Forces binding the atoms
are strong.
Comparatively high
ionization potentials
which increases across
the period.
Smaller atomic size &
have higher ionization
potential. So lesser
tendency to lose valence
electrons.
II. Comparison of Metals & Non-metals – Physical properties
Property
Physical
state
Metals
Solids at room
temperature
Lustre
Lustrous – can be
polished
Hardness
Hard solids
Melting &
Boiling
points
High
Density
High
Malleability
Malleable – Can
be beaten into
sheets
Ductile – can be
drawn into wires
Good conductors
of electricity
Good conductors
of heat
High
Ductility
Conductivity
Tensile
strength
Sonority
Solubility
Alloying
Exceptions
Mercury &
Gallium are
liquids at room
temperature
---
Non - metals
Liquids, gases or
brittle solids
Sodium,
Potassium, Lead
& Mercury
(liquid)
Sodium,
Potassium &
Mercury – Low
M.P & B.P
Sodium,
Potassium &
Calcium – Low
density
Zinc
Soft solids
---
Graphite & Iodine show
luster. (Iodine is
subliming solid)
Diamond (carbon)
Low
Carbon & Silicon – High
M.P & B.P
Low
Diamond (carbon ) – High
density
Non - malleable
Carbon fibre
Zinc & Mercury
Non - ductile
Carbon fibre
Tungsten
Non – conductors
of electricity
Poor conductors
of heat
Low
Graphite and Gas Carbon
Not sonorous
--
Soluble in water
or solvents
(No occurrence
of chemical
change on
dissolution)
Do not form
Carbon (in steel)
Zinc & Mercury
Sonorous – gives Sodium &
a note on striking Potassium
Insoluble in water
or solvents
(Occurrence of
chemical change
on dissolution)
Form alloys
Non - lustrous
Exceptions
Carbon fibre
alloys
III. Comparison of Metals & Non-metals –Chemical properties
Property
Electronic
configuration
Atomicity
Ion formation
On electrolysis
Reducing –
Oxidising nature
Reaction with acids
Nature of oxides
Nature of chlorides
Metals
1, 2 or 3 valence electrons
Monoatomic
Non - metals
{4} 5, 6, or 7 valence electrons
Diatomic, triatomic or polyatomic
 Noble gases are
monoatomic
Lose valence electrons & form cations Gain electrons & form anions
Electropositive in nature
Electronegative in nature
Cations move towards cathode accept Anions move towards anode lose
electrons & get discharged as neutral electrons & get discharged as
atoms (undergo reduction)
neutral atoms or molecoles
(undergo oxidation)
Reducing agents – Donate electrons
Oxidising agents – Accept
during chemical reactions
electrons during chemical
reactions
Active metals react with dilute acids
Non - metals do not react with
(dil. HCl or dil. H2SO4) to liberate
dilute acids (dil. HCl or dil. H2SO4)
hydrogen
to liberate hydrogen
 Form basic oxides {eg: K2O,
 Form acidic or neutral
Na2O, CaO, CuO,MgO, Fe2O3}
oxides
 Soluble basic oxides dissolve in
 Soluble acidic oxides
water to give alkaline solutions
dissolve in water to give
{eg : K2O, Na2O,MgO, CaO}
acidic solutions
 Metallic oxides are
 Non – metallic oxides are
electrovalent
covalent
 Acidic – CO2, SO2, SO3,
 Oxides of Al, Zn & Pb are
NO2, P2O5
amphoteric – They react with
Neutral – CO, NO, N2O,
acids as well as alkalis to give
H2O
salt & water.
 Form electrovalent chlorides
 Form covalent chlorides
 They are non – volatile solids
 They are volatile liquids(eg
o Eg : NaCl, KCl
: PCl3) or solids(eg : PCl5)
 They are soluble in water
 They are insoluble in water
IV. Comparison of General characteristics of Alkali metals & Alkaline earth metals
Characteristics
Position
Elements
Valence electrons
Occurrence
Nature & Bonding
Density
Melting point & Boiling point
Flame test
Reactivity
Action of air
Action of water
Action of acids
Alkali metals
Group 1 [IA]
Li, Na, K, Rb(Rubidium),
Cs(Cesium) & Fr(Francium)
One
 Highly reactive
 Occur in combined
state only
 Compounds of Na & K
are most abundant
 Francium is radioactive
& occurs in traces
 Silvery white
 Soft in nature [can be
cut with knife]
 Have a single valence
electron & metallic
bonding is not so
strong
Alkaline earth metals
Group 2 [IIA]
Be, Mg, Ca, Sr(Strontium),
Ba(Barium), Ra(Radium)
Two
 Reactive
 Occur in combined
state only
 Compounds of Mg &
Ca are most abundant
 Radium is radioactive
& is a rare element
 Silvery white
 Slightly harder than
alkali metals
 Have two valence
electrons & metallic
bonding is stronger
than that in alkali
metals
Low
Higher
Low
Higher
Characteristic colour given to Be & Mg do not give
a flame
characteristic colour
Sodium – golden yellow
Calcium – brick red,
flame, potassium – lilac flame Strontium – crimson / scarlet
red, Barium – apple green
flame.
Strongly electropositive &
Less electropositive & less
highly reactive
reactive
On exposure to moist air
On exposure to moist air
tarnish rapidly {except Li}
tarnish slowly {except Be}
Hence they are kept under
kerosene
React with cold water
Be does not react with water.
vigorously liberating hydrogen Mg reacts with boiling water.
Ca, Sr, Ba react with cold
water.
React with acids vigorously
React with acids less
displacing hydrogen.
vigorously displacing
hydrogen.
Topic:
Metallurgy – Part 2
Uses of Aluminium:
i)
Household purposes:
Aluminium metal is used to make utensils for cooking.
Reasons: Aluminium metal is light, a good conductor of heat, corrosion resistant,
unaffected by food acids and less expensive compared to many other
metals and alloys.
ii)
Packaging:
Thin aluminium foils are used in food packaging , packaging of medicines and in the
manufacture of photographic films..
Reasons: Aluminium metal is light, corrosion resistant, has a bright appearance
and is cheap.
iii)
Paints:
A mixture of aluminium powder and linseed oil is used to make paints for electric
poles. (anti corrosive paints) .
Reasons: Aluminium is corrosion resistant. It is used to prevent the corrosion
of iron.
iv)
Electrical Cables
Aluminium wires are used as cable and transmission wires.
Reasons: Aluminium is a good conductor of electricity.
v)
Alloys:
The alloys of aluminium like Duralumin and Magnalium are used in the manufacture
of aircrafts and tools.
Reasons: The alloys are light, corrosion resistant and have high structural
strength .
vi)
Thermite Welding:
The Thermite process is used for welding of the broken ends of a girder.
Reason: Aluminium is a strong reducing agent. It reduces oxides of less reactive
metals like iron and chromium to the respective metals.
Principle:
The reduction of metal oxides with aluminum powder are accompanied by the release of
huge amount of energy . This reaction is called Thermite or Aluminothermy process.
Procedure:
Thermite process is very useful for the welding of broken metal parts.
When aluminum powder reacts with iron oxide or chromium oxide, a large amount of heat is
released and about a temperature of 3500oC is attained which is enough to weld broken metallic
parts.
Aluminium reduces the oxide of iron or chromium to form iron or chromium metal and itself becomes
aluminium oxide.
The Thermite mixture is Al + Fe2O3. A burning Magnesium ribbon serves to ignite the thermite
mixture.
The reaction is highly exothermic; an enormous amount of heat energy is evolved.
The reduced molten iron sinks and flows into the gap of the girder , thereby the welding occurs.
2Al + Fe2O3
2Al + Cr2O3
Al2O3 + 2Fe + 
Al2O3+ 2Cr + 
Uses of Zinc:
i)
Galvanization:
Definition: Galvanization is the process of coating iron with zinc to prevent the iron from
rusting.
Uses: Galvanised iron ( G.I ) is used to make buckets, roofs and pipes.
Reason: Zinc is used in the galvanization of iron due to the following reasons:
Zinc is placed above iron in the electrochemical series ie. Zinc is more electropositive than iron
Zinc ionizes ( to form Zn2+ ions) more readily than iron.
Procedure: Hot iron sheets are dipped into molten zinc and passed through rollers above 300
C. Thus zinc forms a protective layer over zinc.
Electro galvanizing can also be carried out.
Disadvantages of G.I : Galvanized iron cannot be used to store food because zinc is poisonous.
ii)
Dry Cells: Zinc acts as the negative terminal in the Dry cell.
Reason: Zinc acts as a negative electrode because:
Zinc is highly electropositive , Zinc easily ionizes to form Zn2+ ions
iii)
Alloys : The important alloys of zinc are Brass and Bronze.
Reason: Zinc imparts hardness to the base metal copper in these alloys.
iv)
Cosmetics and medicines: Zinc dust is used in the manufacture of perfumes and in
pharmaceutical preparations.
Reason: Zinc dust is a reducing agent.
Zinc – copper couple is used as a reducing agent in organic chemistry.
Uses of Iron:
After aluminium, iron is the most abundant metal found on Earth’s crust. It has a very wide range of
uses in its various forms. The various forms of iron, their composition and uses are listed below in the
following table:
Form of Iron
i) Pig iron / Cast
iron.
Pig iron is easily
cast and
expands on
solidification
ii) Wrought iron
Carbon
content
2.5 – 5%
Properties
Uses
Brittle, Non- Malleable, Non- ductile,
Cannot be tempered or welded.
Used in drain pipes, gutter
covers and weights
0.1 – 0.25
%
Non- Brittle, Malleable, Ductile, Can
Used in chains, anchors,
be tempered and welded, Can
horseshoes and
withstand strain.
electromagnets.
iii) Steel
0.1 –1.5%
Brittle , Hard, Malleable, Ductile ,Can
Used in ships, automobiles,
be tempered and welded, Has high
machines
structural strength and tensile
strength
iv) Mild steel
0.1 – 0.5%
Malleable, Ductile
Used in nuts and bolts
v) Hard steel
0.5 – 1.5%
Hard, Brittle
Used in tools
There are different types of steel depending on its hardness, brittleness and tensile strength. modify the
properties of steel, different types of heat treatment are given to steel namely Hardening ( Quenching)
and Annealing (Tempering).
Hardening ( Quenching)
Manufacture: Hard steel is heated to
red hot above 800oC and plunged into
cold water or oil.
.
Annealing (Tempering)
Manufacture: Hard steel is heated to
temperatures between 220oC and 300 oC
and cooled slowly for 4 -5 hours.
Property modifications:
Increase in hardness, Increase in
brittleness
Property modifications:
Retains hardness and Brittleness, Increase
in tensile strength
Uses: Specific machine parts.
Uses: Razor blades and Springs.
Rusting of iron ( Corrosion of iron) and Prevention:
Rusting is the process of oxidation of iron when iron is exposed to moisture and air to give a reddish
brown coating of hydrated iron ( III ) oxide. Chemically, rust is hydrated iron ( III ) oxide.
moisture
4Fe + 3O2 + x H2O
2Fe2O3 .xH2O
( Hydrated iron (III) oxide or rust )
Two essential conditions for the rusting of iron:
i) Moisture
ii) Air / oxygen
Prevention of rusting of iron: The methods involve the prevention of both moisture and oxygen from
coming in contact with iron objects.


Painting: Red lead oxide paint is applied on the heavy iron parts in vehicles, machinery etc.
Aluminium paint is applied on telegraph poles and it acts as an anti corrosive paint.
Galvanizing: Iron sheets are dipped in molten zinc and used to make buckets, roofs, pipes etc.,
Experiment to demonstrate that both moisture and oxygen are necessary for rusting:
Test tube A: The polished iron nails get rusted since both moisture ( from tap water) and oxygen are
present.
Test tube B : The polished iron nails do not get rusted since boiling removes the oxygen dissolved in
wate and the layer of oil cuts off the oxygen from air. The test tube is sealed.Hence even though
moisture is present, the nails do not rust due to the absence of oxygen.
Test tube C: The polished iron nails do not get rusted . The anhydrous calcium chloride acts as a drying
agent and absorbs moisture from the air inside the test tube . Hence even though oxygen is present,
the nails do not rust due to the absence of moisture.
This experiment proves that both moisture and oxygen are required for rusting.
Alloys:
An alloy is a homogeneous mixture of two or more metals mixed in definite proportions so as to obtain
desired properties.
It is usually prepared by melting the components together and solidifying the mixture. So the
components must be miscible in liquid state and should not separate on solidification.
The properties of the alloy are intermediate between those of the constituent metals.
The metal present in the larger proportion in the alloy is called the base metal. Eg. In brass, the base
metal is copper.
If the base metal is mercury , the alloy is termed as amalgam.eg: Na /Hg amalgam.
List of some important alloys, their composition and uses:
Name of
alloy
i) Brass
ii) Bronze
Composition
Cu ( 60 -80% ),
Zn ( 40 -20% )
Base metal
Copper
iii)
Duralumin
Cu (80% ),
Sn ( 19% ),
Zn (1%)
Al (95%), Cu (4%),
Mg(0.45%), Mn(0.5%)
iv) Solder
(Fuse metal)
Pb ( 50 % ),
Sn (50 %)
_______
v) Stainless
steel
Fe (75%),
Ni (10%), Cr(15%),
C (0.5%)
Iron
Copper
Aluminium
Properties
Uses
Hard , lustrous, easily
cast, malleable and
ductile
Hard, attractive ,takes
up polish
Electrical
fittings , Medals
Stronger than Al .
Aluminium imparts
lightness while Mg
imparts strength
The melting point of the
alloy( 180oC ) is lower
than Sn and Pb. The
melting point is lowered
and the alloy has high
tensile strength.
Ni, Cr – imparts lustre,
Cr- prevents corrosion,
C- imparts hardness
Statues, medals ,
coins
Aircrafts, light
tools, cooker, ships
Electrical fuse,
Electrical welding
and soldering
Utensils, cutlery,
automobiles
vi) Nickel
steel
Fe (97%),
Ni (2%),
C (1%)
Iron
Elastic .
Ni imparts high tensile
strength
Cables, aircraft
parts
Some other alloys:
Name of alloy
Composition
i)German silver
Cu and Zn
Base
metal
Cu
ii) Gun metal
Cu, Zn, Sn, Pb
Cu
iii) Bell metal
iv) Magnalium
Cu, Sn
Al, Mg
Cu
Al
v) Type metal
Pb, Sn, Sb
Pb
Topic:
Properties
Uses
Hard, silvery, takes up
polish a Zn
Hard, brittle, easily cast
Decorative articles
Brittle, sonorous
Light, tough, corrosion
resistant
Low m.p, easily cast,
expands easily on
solidification
Metallurgy – Part 3
Terms used in Metallurgy:

Metallurgy:

Mineral:

Ore:

Matrix or Gangue:

Flux:
Eg: In the extraction of iron from iron ore,
Some common ores of iron, zinc and aluminium:
Barrels, cannons,
bearings
Bells, Gongs
Aircraft, scientific
tools
Printing blocks
Ores of Aluminium:
Chemical Formula
Common name
Chemical name
Chemical Formula
Ores of Zinc:
Common name
Chemical name
Chemical Formula
Ores of Iron:
Common name
Chemical name
Chemical Formula
Some metals like Au and Pt occur native (free or uncombined state)
Steps involved in metallurgical operations:
Step I:
Step II :
Step III:
Step IV:
Concentration of the Ore (Ore dressing)
Conversion of ore to oxide(Roasting or Calcination )
Reduction of metallic oxide to metal
Refining of impure metal to get pure metal
Step I : Concentration of the ore or ore dressing:
The following methods may be used for concentration of ores:
i)
Magnetic separation:
Principle:
Used to separate
eg:
OR
eg:
Process:
Diagram :
ii)
Froth Floatation: Used for the concentration of _______________________ores like
__________________________________________.
Principle:
Process:
Diagram:
iii)
Hydrolytic Method or Gravity Separation:
Principle:
Process:
Diagram:
iv)
Chemical method: Addition of a chemical substance. Eg: Addition of conc. NaOH
solution in the Bayer’s process used in the concentration of bauxite ore during the
extraction of aluminium.
Step II: Concentration of ore to oxide since oxides are easily reduced.
This step is not needed if the ore is an oxide.
There are two methods to convert non- oxide ores to oxides : Roasting and Calcination.
Roasting:
eg: i)
ii)
Calcination:
eg: i)
ii)
Distinguish between Roasting and Calcination:
Roasting
1.
1.
2.
2.
3.
3.
Calcination
Step III:
Reduction of oxides of metals to the metals – Most important step in metallurgy
The three main methods used for reduction of oxide ores to the respective metals are:



Electrolytic reduction : involves extraction of the metal by the electrolysis of fused salts like
chlorides, oxides etc.,
Chemical reduction : involves extraction of the metal by the reduction of metallic oxides
using common reducing agents like coke, carbon monoxide, hydrogen etc.,
Thermal reduction
: By the thermal decomposition of the oxides of metals which are
unstable to heat like the oxides of silver and mercury
The method selected for the reduction of the oxide depends on the position of the metal in the
Metal Activity series:
Activity series Characteristics of metal and its
Method of extraction and equations
ore
K
Metals
Method:
eg 1)
Metallic ores
eg 2)
Al
Zn
Metals
Method:
eg i)
ii)
Metallic ores
H
iii)
Cu
iv)
Before the reduction, the ores are
converted to oxides since oxides are easily
reduced.
Sulphide ores are roasted :
Equation:
Carbonate ores are calcined:
Equation:
Once the oxide ores are obtained, they are
then subjected to chemical reduction.
Hg
Metals
Method:
eg i)
Ag
Metallic ores
eg 2)
Step IV: Refining of impure metal obtained after reduction to get pure metal
The following methods may be used:

Distillation refining: Used for
Principle:

Liquation refining: Used for
Principle :

Oxidation refining: Used for
Principle:

Electrolytic refining: Used for
Principle:
Metallurgy – part 4 : Extraction of aluminium from Bauxite
Aluminium is the most abundant metal on the Earth’s surface.
The important ores of aluminium are bauxite , cryolite and corundum.
Generally, aluminium is extracted from bauxite ore ( Al2O3.2H2O )
Steps involved in the extraction of aluminium from Bauxite:
Step 1:
Step 2:
Step 3:
Step 4:
Step 1: Concentration of bauxite ore or Ore dressing: Chemical method (Bayer’s process)
In this step, impure bauxite ( Al2O3.2H2O ) is converted to pure alumina ( Al2O3)

Conversion of impure bauxite to sodium aluminate:
Reagent added:
Procedure:
Principle:
Equation:

Conversion of sodium aluminate to aluminium hydroxide:
Equation:
Procedure:

Conversion of aluminium hydroxide to pure alumina:
Equation:
Procedure:
Step 2: Roasting or Calcination not required for oxide ore
Step 2: Electrolytic reduction of pure alumina (Al2O3 ) : Hall Heroult’s process
Electrolyte:
Electrolytic Cell:
Electrodes (inert) :
Cathode:
Anode:
Temperature:
Current:
Electrolytic reactions:
Ionisation:
Cathode:
Reason:
Anode:
Products:
Diagram:
Hall Heroult's process
Why is electrolysis used for the reduction of alumina?
What were the difficulties encountered during the reduction of alumina ?
Why are fused cryolite and fluorspar added to the electrolytic mixture?
Why is a layer of coke sprinkled over the electrolytic mixture?
Why should the graphite anodes be continuously replaced during the electrolysis?
How is the metal removed?
Which arrangement indicates that it is time to add more electrolyte?
Aluminum obtained by Hall Heroult’s process is 99.5% pure and has to be refined electrolytically.
Step 4: Refining of impure Al to obtain pure Al by electrorefining ( Hoope’s process)
3 layers in the electrolytic tank:
Upper layer:
Middle layer:
Lower layer:
Diagram:
Hoope's process
Electrolytic reactions:
Cathode:
Anode:
Collection:
Extraction of Zinc:
1. Concentration of ore: By___________________
2. Roasting:
3. Reduction:
4. Refining of zinc spelter to get pure zinc:
Calcination:
Extraction of iron from haematite:
1. Concentration of ore :
2. Reduction: Reducing agent:
Flux :
3 zones in the Blast furnace:
Pig iron:
Conversion of pig iron to steel:
_________________________________________