CENTRAL INSTITUTE OF PLASTICS ENGINEERING & TECHNOLOGY
Question Bank solution
2 MARK ---QUESTION
COURSE : DPMT
SEMESTER: II
SUBJECT : Engineering Chemistry
3 MARK—QUESTION
------
Ques 1:Define Atomic number, atomic mass and molar mass.
Ans:The atomic number or proton
number (symbol Z) of a chemical element is
the number of protons found
in the nucleus of
every atom of
that element. uely identifies a chemical element. It is
identical to the charge number of
the nucleus. In an uncharged atom,
the atomic number is also equal to the number of electrons.
Together, the number of protons and the number of neutrons
determine an element’s mass number: mass number = protons +
neutrons.
A property closely
related to an atom’s mass number is its atomic mass. The atomic
mass of a single atom is simply its total mass and is typically expressed in
atomic mass units or amu. By definition, an atom of carbon with six neutrons,
carbon-12, has an atomic mass of 12 amu.
The molar mass of a chemical compound is
defined as the mass of
a sample of that compound divided by the amount
of substance in that sample, measured in moles.[1] The
molar mass is a bulk, not molecular, property of a substance. The molar mass is
an average of many instances of the compound, which often vary
in mass due to the presence of isotopes. Most
commonly, the molar mass is computed from the standard
atomic weights. The molar mass is appropriate for converting between the mass
of a substance and the amount of a substance for bulk quantities.
Ques 2: Write electronic
configuration for the following elements ------
I) O(8) II)
Ca(20) III) Cu(29)
Ans:O = 1s2,2s2,2p4
Ca = 1s2,2s2,2p6,3s2,3p6,4s2
Cu = 1s2,2s2,2p6,3s2,3p6,3d10,4s1
Ques 3:
Write difference between Orbit and Orbital.
|
Ans: Difference between Orbit and Orbitals |
|
|
Orbit |
Orbitals |
|
An orbit is the simple planar representation of an electron. |
An orbital refers to the dimensional motion of an electron
around the nucleus in a three dimensional motion. |
|
It can be simply defined as the path that gets established in
a circular motion by revolving the electron around the nucleus |
An orbital can simply be defined as the space or the region
where the electron is likely to be found the most. |
|
The shape of molecules cannot be explained by an orbit as they
are non directional by nature. |
The shapes of the molecules can be found out as they are
directional by nature. |
|
An orbit that is well defined goes against the Heisenberg
principle. |
An ideal orbital agrees with the theory of Heisenberg’s
Principles. |
Ques 4: Define Pauli’s exclusion law, with example.
Ans: The
Pauli Exclusion Principle states that, in an atom or molecule, no two electrons
can have the same four electronic
quantum numbers. As an orbital can contain a maximum of
only two electrons, the two electrons must have opposing spins. This means if
one is assigned an up-spin ( +1/2), the other must be down-spin (-1/2).Maximum
3 quantum numbers will be same.
Ques 5: Explain Aufbau principle, with example.
Ans: TheAufbau principle dictates the manner in which electrons are
filled in the atomic orbitals of an atom in its ground state. It states that
electrons are filled into atomic orbitals in the increasing order of orbital
energy level. According to the Aufbau principle, the available atomic orbitals
with the lowest energy levels are occupied before those with higher energy
levels.The word ‘Aufbau’ has German roots and can be roughly translated as
‘construct’ or ‘build up’. A diagram illustrating the order in which atomic
orbitals are filled is provided below. Here, ‘n’ refers to the principal quantum number and
‘l’ is the azimuthal quantum number.
The Aufbau principle can be used to understand the location of
electrons in an atom and their corresponding energy levels. For example, carbon
has 6 electrons and its electronic configuration is 1s22s22p2.
Ques 6: Define Hund’s rule of maximum multiplicity, with example.
Ans: According to Hund’s rule:
Before the double occupation of any orbital, every orbital in the sub level is singly occupied.For the maximization of total spin, all electrons in a single occupancy orbital have the same spin.An electron will not pair with another electron in a half-filled orbital as it has the ability to fill all its orbitals with similar energy. A large number of unpaired electrons are present in atoms which are at the ground state. If two electrons come in contact they would show the same behaviour as two magnets do. The electrons first try to get as far away from each other as possible before they have to pair up.
Hund’s Rule
In above configurations ‘a’ and ‘e’ are correct while ‘b’, ‘c’
& ‘d’ are not correct configurations.
Ques 7: Define followings with example ----- i) Isotope ii) Isobar iii) Isoelectron iv) isotones
Ans: ISOTOPES-: Isotopes are atom have same
atomic number but different mass number or atomic mass.Ex- hydrogen
has 3 isotopes as protiumdutrium and tritium having same atomic number 1 with
different mass number 1,2,3.
ISOBARS-: Isobars are atoms of different
elements which have same mass number but different atomic number.Ex- argon
and calcium have same mass number 40 but different atomic number 18,20.
ISOELECTRON-: Isoelectronic are those species
(atoms)or molecules or ions; having same number of electrons in them.Ex-Like
Na+ , Mg2+,Al3+, All these three ions have same number of electrons present in
them i.e, 10.
ISOTONES-: Isotone are the atom of
different element which contain same number of neutron with different mass
number and atomic number.Ex- silicon
and phosphorous have same number of neutron 16 with different mass number 30,31
and atomic number 14,15.
Ques 8: Explain Bohr’s atomic model.
Ans: Bohr Atomic Model:
A Danish physicist named Neil Bohr in 1913 proposed the Bohr atomic
model.According to Bohr Atomic model, a small positively charged nucleus is
surrounded by revolving negatively charged electrons in fixed orbits. He
concluded that electron will have more energy if it is located away from the
nucleus whereas the electrons will have less energy if it located near the
nucleus.
Postulates of the Bohr Atomic Model
Electrons revolve around the nucleus in a fixed circular path termed “orbits” or “shells” or “energy level.” The orbits are termed as “stationary orbit.”
Every circular orbit will have a certain
amount of fixed energy and these circular orbits were termed orbital shells.
The electrons will not radiate energy as long as they continue to revolve around
the nucleus in the fixed orbital shells.
The different energy levels are denoted by
integers such as n=1 or n=2 or n=3 and so on. These are called as quantum
numbers. The range of quantum number may vary and begin from the lowest energy
level (nucleus side n=1) to highest energy level. Learn the concept of an
Atomic number here.
The different energy levels or orbits are
represented in two ways such as 1, 2, 3, 4… or K, L, M, N…..
shells. The lowest energy level of the electron is called the ground
state. Learn the concept of Valency here in detail here.
The change in energy occurs when the electrons
jump from one energy level to other. In an atom, the electrons move from lower
to higher energy level by acquiring the required energy. However, when an
electron loses energy it moves from higher to lower energy level.
Therefore,
1st orbit (energy level)
is represented as K shell and it can hold up to 2 electrons.
2nd orbit (energy level)
is represented as L shell and it can hold up to 8 electrons.
3rd orbit (energy level)
is represented as M shell and it can contain up to 18 electrons.
4th orbit (energy level) is represented as N Shell and it can contain maximum 32 electrons.
Ques
9: Calculate the molecular weight of following molecules ------
I) Na3PO4 II) CO2
III) Al2(SO4)3 IV) KNO3 V) CaCO3
(At wt. ofNa = 23, P=32,
O=16, C=12, Al= 27, S=32, K=39, N=14,Ca=40)
Ans:i) 23(1)+ 31+ 16(4) = 164 ii) 12+16(2) = 44 iii) 27(2)+ 32(3)+16(12) = 342
iv) 39+ 14+ 16(3) = 101 v) 40+ 12+ 16(3) = 100
Ques 10: What are electrovalent bonds ? explain with example.
Ans: Electrovalent bonding-An electrovalent bond is formed when a metal atom transfers one or more electrons to a non-metal atom.
Some other examples are: MgCl2, CaCl2,
MgO, Na2S, CaH2, AlF3, NaH, K2O,
KI, NaBr, CaH2 etc.
Conditions
for formation of Electrovalent Bond
* The atom which changes into cation (+ ive ion) should possess 1, 2 or 3 valency electrons. The other atom which changes into anion (–ve ion) should possess 5, 6 or 7 electrons in the valency shell.
* A high difference of electronegativity (about 2) of the two
atoms is necessary for the formation of an electrovalent bond. Electrovalent
bond is not possible between similar atoms.
* There must be overall decrease in energy i.e., energy must be
released. For this an atom should have low value of Ionisation
potential and the other atom should have high value of electron
affinity.
Ques 11: Explain about covalent bonding, with example.
Ans: A
covalent bond is a chemical link between two atoms or
ions in which the electron pairs are
shared between them. A covalent bond may also be termed a molecular bond. Covalent
bonds form between two nonmetal atoms with identical or
relatively close electronegativity values. The term "covalent
bond" first came into use in 1939, although Irving Langmuir introduced the
term "covalence" in 1919 to describe the number of electron pairs
shared by neighboring atoms.The electron pairs that participate in a covalent
bond are called bonding pairs or shared pairs. Typically, sharing
bonding pairs allows each atom to achieve a stable outer electron shell,
similar to that seen in noble gas atoms.
Examples – CH4, NH3, H2O, CCl4, CO2 etc
Ques 12: Explain coordinate covalent bonding, with example.
Ans: A coordinate covalent bond is also known as a dative bond, or a dative covalent bond.It is formed when lone pair of electron shared only by one atom of sharing. An atom with a lone pair of electrons (non-bonding pair of electrons) is capable of forming a coordinate covalent bond.Ex –
NH4+,
H2O2,H3O+ etc
Ques 13: Define H-Bonding with example.
Ans: A
hydrogen bond is an attraction between two atoms that already participate in
other chemical bonds. One of the atoms is hydrogen, while the other may be any
electronegative atom, such as oxygen, chlorine, or fluorine. It is of 2 types
---
i) Intermolecular H- boning: it is form between two separate molecules. e.g.- H2O, NH3, HF
ii) Intramolecular H- bonding: it is form within same molecule.
e.g.- o-fluro phenol, o-amino phenol.
Ques 14: H2O is liquid but H2S is gas ? why?
Ans: In water there is a intermolecular H-bonding present.Whereas in H2S ‘S’ can’t form H bonding due to large size and low electronegativity, thus molecules in H2S situated at a distance and physical state will be gaseous.
Ques 15: Differentiate between Polar and Non polar covalent bonds.
|
Ans:Difference
between Polar and Nonpolar |
|
|
POLAR |
NONPOLAR |
|
Asymmetrical |
Symmetrical |
|
Has
electrical poles |
Does
not have electrical poles |
|
One
end of molecule has positive whereas the other end has negative charge |
Does
not have profusion of charges at opposite ends |
|
H
bonds occur in polar bonds |
Van
derwaal interactions between nonpolarbonds |
|
At
Least one polar covalent is present in all polar molecules |
Nonpolar
covalent is not present in all nonpolar molecules |
|
Charge
separation |
No
charge separation |
|
Dipole
moment |
No
dipole moment |
|
Example:
Water |
Example:
Oil |
Ques 16: Differentiate sigma and pai bonds.
|
Ans: Difference
Between Sigma and Pi bond |
|
|
Sigma
Bond |
Pi
Bond |
|
During
sigma bond formation overlapping orbitals can be either one hybrid and one
pure orbital or two pure orbitals and two hybrid orbitals. |
During
pi bond formation overlapping orbitals are always two unhybridizedorbitals. |
|
Sigma
bond exists independently and allows free rotation. |
Pi-bond
always exists along with sigma bond and the rotation is restricted. |
|
Sigma
bonds are stronger bonds. |
Pi
bonds are usually less powerful compared to sigma bonds. |
|
Sigma
bonds are formed first when atoms interact. |
Pi
bonds are formed after the formation of sigma bonds. |
|
During
the bonding between two atoms, Only
one sigma bond is formed. |
Here
two pi bonds can exist between two atoms. |
|
Sigma
bond has cylindrical charge symmetry around the bond axis. |
No
symmetry exists in pi bonds. |
|
Atoms
with sigma bonds can be highly reactive. |
Atoms
with pi bonds are less reactive in nature. |
|
Sigma
bond can be used to determine the shape of a molecule. |
Pi
bond cannot be used for the same purpose. |
Ques 17: Calculate number
of sigma and pai bonds in following compounds ----
C6H6, CO2, CH3COOH, C2H2, C2H4, C2H6
Ans: C6H6 = 12 Sigma, 3 Pai CO2 = 2 Sigma, 2 Pai CH3COOH = 7 Sigma, 1 Pai C2H2 = 3 Sigma,2Pai C2H4 = 5 Sigma, 1 Pai C2H6 = 7 Sigma, zero Pai
Ques 18: Explain Lewis acid base theory with example.
Ans: In 1923 G. N. Lewis suggested another way of looking at the reaction between H+ and OH- ions. In the Brnsted model, the OH- ion is the active species in this reaction it accepts an H+ ion to form a covalent bond. In the Lewis model, the H+ ion is the active speciesit accepts a pair of electrons from the OH- ion to form a covalent bond.
In the Lewis theory of acid-base reactions, bases donate pairs of
electrons and acids accept pairs of electrons. A Lewis acid is
therefore any substance, such as the H+ ion, that can accept a
pair of nonbonding electrons. In other words, a Lewis acid is an electron-pair
acceptor. A Lewis base is any substance, such as the OH- ion,
that can donate a pair of nonbonding electrons. A Lewis base is therefore
an electron-pair donor.One advantage of the Lewis theory is the way
it complements the model of oxidation-reduction reactions. Oxidation-reduction
reactions involve a transfer of electrons from one atom to another, with a net
change in the oxidation number of one or more atoms.
Ques 19: Define conjugate
acid-base theory. Write the conjugate acid pair of followings ----
NH3, OH-, Cl-, HSO4-, HCO3-, H2O
Ans: The Bronsted-Lowry acid-base theory includes the concepts of
conjugate acids and conjugate bases. When an acid dissociates into its ions in
water, it loses a hydrogen ion. The species that is formed is the acid's
conjugate base. When a base accept a hydrogen ion, The species that is formed
is the base's conjugate acid. The
conjugate base is able to gain or absorb a proton in a
chemical reaction. The conjugate acid donates the proton or
hydrogen in the reaction.
In an acid-base reaction, the chemical reaction is:
Acid + Base ⇌
Conjugate Base + Conjugate Acid
chemical
reaction between a conjugate acid and a conjugate base is:
HX + H2O ↔ X− + H3O+
In above reaction, HX is acid and X- is its conjugate
base pair while H2O is base and H3O+ is its conjugate acid pair.
Ques 20: What
do you mean by pH scale? Mention the pH
range of followings ---
Gastric juice, Lemon,
tomato juice, milk, blood,
pure water
Ans: pH is
the negative logarithm of the hydrogen ion concentration:pH = −log [H+]
The square brackets around the H+ automatically mean "concentration" to a chemist. What the equation means is just what we said before: for each 1-unit change in pH, the hydrogen ion concentration changes ten-fold. Pure water has a neutral pH of 7. pH values lower than 7 are acidic, and pH values higher than 7 are alkaline (basic).
pH of --- Gastric juice =
3, lemon = 2.4, tomato juice = 4.4, milk = 6.6,
blood = 7.5, pure water = 7
Ques 21: Calculate
the pH of 0.01 M KOH solution at 298 K.
Ans: pH= −log [H+] , [OH- -] = 0.01 M = 10-2
[H+] [OH -]= 10-14M, [H+] = 10-14 /10-2 = 10-12
pH = -log[10-12]
= 12
Ques 22:
Define Normality with their formula.
Ans: Normality (N) is defined as the number
of gram equivalents of solute dissolved in
One litre solution.normality = number of gram equivalents /1 L of solution
number of gram equivalent
= mass of solute / equivalent
weight of solute.
Ques 23: How will you calculate the Equivalent weight of acids, bases and salts.
Ans: Equivalent weight of acids
= molar mass of acid / basicity
of acid
Basicity of acids is no of ionizable hydrogen ion present in acid.
Equivalent weight
of bases = molar mass of base / acidity of base
acidity of bases is no of ionizable hydroxyl ion present in base.
Equivalent weight of salts = molar mass of salt / total no. of cationvalency.
Ques 24: Differentiate molarity and molatity.
Ans: Molarity (M) is
defined as the number of moles of
solute per liter of solution.
molarity = moles of solute/ per liters of solution
Molality (m) is defined as the number of moles of solute per kilogram of solvent.
molality = moles of solute/kilograms of solvent
Molarity is a measurement of the moles in
the total volume of the solution, whereas molality is
a measurement of the moles in relationship to the mass of the solvent.
When
water is the solvent and the concentration ofthe solution is low, these
differences can be negligible (d = 1.00 g/mL). However, when the density of the
solvent is significantly different than 1 or the concentration of the solution
is high, these changes become much more evident.
Example:
Compare the molar and molal volumes of 1 mol of a solute dissolved in CCl4 (d
= 1.59/mL).
For
a 1 Molar solution, 1 mol
of solute is dissolved in CCl4 until the final volume of
solution is 1 L.
For a 1 molal solution, 1
mol of solute is dissolved in 1 kg of CCl4.
1 kg of CCl4 × (1,000 g/1 kg) × (mL/1.59 g) = 629 mL CCl4
Ques 25: How to prepare N/10 Oxalic
acid solution in one litre of water?
Ans:
by using the formula W = E N V / 1000
= 90 X 0.1 X 1000 / 1000 = 9 gm
Now, 9 gram oxalic acid will be
dissolve in one lit of water to prepare N/10 oxalic acid solution.
Ques 26: What do you mean by buffer solution? Differentiate between acid buffer and base buffer solutions.
Ans:
A buffer solution is chemical
solution which resists change to its pH or
acidity.It is a solution in
water of a mixture of a weak acid or base and
its salt. The pH of
the solution changes very little when a small amount of strong acid or
base is added to it. Buffer solutions are used as a means of keeping pH at a
nearly constant value in a wide variety of chemical applications. Many life
forms have a relatively small pH range; an example of a buffer solution
is blood.
Buffer solutions may be of two types: acidic and basic.
Acidic : A solution of mixture of weak acid and a salt of
this acid with a strong base.
eg. CH3COOH + CH3COONa
Basic : A solution of a mixture of weak base and its salt
with a strong acid .
eg. NH4OH + NH4Cl
If you add acid to the solution, the concentration of H+ ions will increase; to keep equilibrium a small number of ions will be combined (forming salt and reducing the concentration of H+ ion in the solution). If you add base the concentration of H+ ion will reduce (by consumption or combining) and so a small amount of salt will break into ions and maintain the pH.
Ques 27: Define transport number and its applications.
Ans: The transport number, t_i, describes the fraction of the
total current that is carried by the ion, i. This number depends on
the relative mobility of the ions, and ultimate gives the relative contribution
to conductivity of each of the ions. The sum of transport numbers over all the
ions in a solution is always equal to 1.
Ex. In a cell where the electrolyte is 1 M HCl and a current is going between the the anode and the cathode, H+ and Cl- must carry all of the current. In this case, H+ is moving towards the cathode and Cl- is moving towards the anode. If the transport number of Cl-, i.e, t_Cl- is 0.7, this means that 70% of the total current is carried by the Cl-, and that more Cl- ions are moving towards the cathode than H+ ions moving towards the anode. Subsequently, t_H+ is 0.3.
Ques 28: Find out Normality of solution having 40 gm of NaOH in 500 ml solution.
Ans: W = E N V / 1000 by this formula 40 = 40 X N X 500 / 1000 , N = 2
Ques 29: What is an electrolyte? Give its classification.
Ans: Electrolytes are substances which, when dissolve in water,
break up into cations and anions. They have ability to conduct electric current
.these are of two types –
i) strong electrolyte – they ionize 100% when dissolve in water
ii) weak electrolyte – they ionize partially when dissolve in
water.
|
Strong
Electrolytes |
strong acids |
HCl, HBr, HI, HNO3, HClO3, HClO4,
and H2SO4 |
|
strong bases |
NaOH, KOH, LiOH, Ba(OH)2, and Ca(OH)2 |
|
|
salts |
NaCl, KBr, MgCl2, and many, many more |
|
|
Weak
Electrolytes |
|
|
|
weak acids |
HF, HC2H3O2 (acetic acid), H2CO3 (carbonic
acid), H3PO4 (phosphoric acid), and many more |
|
|
weak bases |
NH3 (ammonia), C5H5N
(pyridine), and several more, all containing "N" |
salts NH4Cl, (NH4)2CO3 and all ammonium salts
Ques 30: Differentiate
between Electrolysis and Electroplating.
|
Ans: Electrolysis |
Electroplating |
|
Electrolysis
refers to the breaking apart of a molecule by the means of electrochemical
reaction. |
Electroplating
refers to the passage of current through the solution with metal such that it
gets deposited on one of the electrodes. |
|
Electrolysis
is good for carrying out the non-spontaneous chemical reactions. |
Electroplating
is good when metallic ions needs to be coated on other metal. |
|
Electrolysis
is used for the extraction of metals from its ores. |
Electroplating
is used for coating metals on pure metals. |
|
Finds
applications in electrosynthesis, mercury cell process, and electrorefining. |
Finds
application in preventing metals from corrosion. |
Ques 31: Explain
difference between cell and battery.
|
Ans: Basis for Comparison |
Cell |
Battery |
|
Definition |
The single unit device which converts the chemical energy into
electrical energy |
It is the collection of electrochemical cells which either
connects in series or in parallel |
|
Symbol |
 |
 |
|
Types |
Dry Cell, Wet Cell , Reserve Cell and Fuel Cell. |
Primary battery and Secondary battery. |
|
Specification |
Light and compact |
Heavy |
|
Power |
Supply power for a short time. |
Supply power for a long time. |
|
Applications |
Clocks, lamp, radio, remote control devices etc.. |
Automobiles, inverter, emergency light etc. |
|
Cost |
Cheap |
Costly |
Ques 32: Write major
difference between Organic and Inorganic compounds.
|
Ans: |
Organic
Compounds |
Inorganic
Compounds |
|
1. |
Organic
compounds are characterized by the presence of carbon atoms in them |
Inorganic
compounds do not have carbon atoms in them |
|
2. |
Organic
compounds consisting of hydrogen, oxygen, carbon, and their other derivatives |
They
do not possess hydrogen or oxygen and their derivatives |
|
3. |
Organic
compounds are said to be more volatile and also highly inflammable |
These
compounds are not inflammable and are non-volatile in nature |
|
4. |
These
compounds exist in the form of Solids, gases, and liquids. |
These
exist as solids |
|
5. |
These
are insoluble in water |
These
are soluble in water and also non-soluble in some of the organic solutions. |
|
6. |
These
compounds have the carbon-hydrogen bonds |
These
does not have the carbon-hydrogen bonds |
|
7. |
Organic
compounds are mainly found in most of the living things |
These
compounds are found in non-living things |
|
8. |
Organic
compounds form covalent bonds |
Inorganic
compounds form ionic bonds between the atoms of molecules |
|
9. |
In
most of the aqueous solutions, these are poor conductors of heat and
electricity |
In
aqueous solutions, these are known to be good conductors of heat and
electricity |
|
10. |
Examples
of organic compounds include fats, nucleic acids, sugars, enzymes, proteins,
and hydrocarbon fuels |
The
example for inorganic compounds includes non-metals, salts, metals, acids,
bases, substances which are made from single elements |
|
11. |
These
have high melting and boiling points |
These
have low melting and boiling points compared to organic compounds |
|
12 |
These
are biological and more complex in nature |
These
are of mineral and not much complexity in nature |
|
13 |
Organic
compounds cannot make salts |
Inorganic
compounds can make salts |
|
14 |
The
rate of reaction is slow in organic compounds |
Inorganic
compounds have a high rate of reaction |
Ques 33: What do you mean by Isomerism? mention its classification.
Ans:
Isomerism is the phenomenon in which more than one
compounds have the same chemical formula but different chemical structures.
Chemical compounds that have identical chemical formulae but differ in
properties and the arrangement of atoms in the molecule are called isomers.
Therefore, the compounds that exhibit isomerism are known as isomers.The word
“isomer” is derived from the Greek words “isos” and “meros”, which mean “equal
parts”. This term was coined by the Swedish chemist Jacob Berzelius in the year
1830.
Classification
There are two primary types of isomerism, which can be further
categorized into different subtypes. These primary types are Structural
Isomerism and Stereoisomerism. The classification of
different types of isomers is illustrated below.
Ques 34 Difine chain isomerism with example.
Ans:
Chain Isomerism
It is also known as skeletal isomerism.
The components of these isomers display differently branched
structures.
Commonly, chain isomers differ in the branching of carbon
An example of chain isomerism can be observed in the compound C5H12,
as illustrated below.
Ques 35: Explain position isomerism with example.
Ans:
Position Isomerism
The positions of the functional groups or substituent atoms are
different in position isomers.
Typically, this isomerism involves the attachment of the functional groups to different carbon atoms in the carbon chain.An example of this type of isomerism can be observed in the compounds having the formula
C3H7Cl.
Ques36 Explain about Funtional isomerism with example.
Ans: Functional Isomerism
It is also known as functional group isomerism.
As the name suggests, it refers to the compounds that have the
same chemical formula but different functional groups attached
to them.
An example of functional isomerism can be observed in the
compound C3H6O.
CH3 CH2 CHO (-CHO) group & CH3COCH3 (>C=O) group
Ques 37: Define Metamersim with example.
Ans: When compounds having same molecular formula but different
structural formula due to difference
Of alkyl group around functional group.
Example --- CH3 NH CH2CH2CH3 & CH3CH2 NH CH2CH3
CH3 O CH2CH2CH3 & CH3CH2 O CH2CH3
Ques 38 : Define tautomerism with example.
Ans: Tautomerism-- it is the existence of two or
more chemical
compounds that are capable of facile
interconversion, in many cases merely exchanging a hydrogen atom between
two other atoms, to either of which it forms a covalent bond. Unlike
other classes of isomers, tautomeric compounds exist
in mobile equilibrium with
each other, so that attempts to prepare the separate substances usually result
in the formation of a mixture that shows all the chemical and physical properties
to be expected on the basis of the structures of the components.
The most common type of tautomerism is that involving carbonyl, or keto, compounds and unsaturated hydroxyl compounds, or enols; the structural change is the shift of a hydrogen atom between atoms of carbon and oxygen, with the rearrangement of bonds as indicated
Ques 39: Define salient features of Homologous series.
Ans: Homologous series are 'families' of organic compounds. They
share common characteristics:
They all contain the same functional group. This gives the
homologous series name.
They differ in formula from one member to the next by one -CH2-
unit and differ in molecular weight by 14 amu.
They show a steady change in physical properties from one member
to the next
They display similar chemical properties
Ques 40: Write the IUPAC
name of following compounds -----
1) CH2(OH)CH2(OH) 2) CHO CH2 CH(OH) CH3 3) COOH CH(NO2) CH2
CH(Cl) CH3
4) C6H5
CH2CH2COOH 5) CH3CH2COCH2CH2CH2CH3 6) CH3C(CH3)2CH2
C(Br)(Cl)CH3
Ans: 1) Ethane-1,2-diol
2) 3-hydroxybutanal 3)
4-chloro-2-nitropentanoic acid
4)
3-phenylpropanoic acid 5)
heptan-3-one 6)
4-bromo-4-chloro-2,2-dimethylpentane
Ques 41 Define fuel and mention the characteristics of good fuels.
Ans: Fuels are any
material that store potential energy in forms, which upon burning in oxygen
liberates heat energy.Calorific value of fuel is the total quantity of heat
liberated when a unit mass or volume of fuel is completely burnt.
characteristics of a good fuel are -----1) high calorific value
2) it should be abundantly available on earth
3) it should be economically profitable
4) Low moisture content
5) easy to transport and store
Ques 42: Mention the advantage of liquid fuel over soild fuel.
Ans: 1) The
handling of liquid fuels is easier and they require less storage space.
2) The combustion of
liquid fuels is uniform.
3) The solid fuels have
higher percentage of moisture and consequently they burn with
great difficulty. However, liquid fuels can be burnt with a fair
degree of ease and attain
high temperature very quickly compared to solid fuels.
4) The waste product of
solid fuels is a large quantity of ash and its disposal becomes a
problem. However, liquid fuels leave no or very little ash
after burning.
5) The firing of liquid
fuels can be easily controlled. This permits to meet the variation in
load demand easily.
Ques 43: Define calorific value and differentiate HCV A& LCV.
Ans: Calorific value is the
amount of heat energy present in food or fuel and which is determined by the
complete combustion of specified quantity at constant pressure and in normal
conditions. It is also called calorific power. The unit of calorific value is
kilojoule per kilogram i.e. KJ/Kg.
Higher Calorific Value (HCV) or Gross Calorific Value:
When 1 kg of a fuel is burnt, the heat obtained by
the complete combustion after the products of the combustion are
cooled down to room temperature (usually 15 degree Celsius) is called
higher calorific value of that fuel.
Lower Heating Value (LLV) or Net Calorific
Value: When 1 kg of a fuel is completely burned and the
products of combustions are not cooled down or the heat carried away
the products of combustion is not recovered and the steam produced in
this process is not condensed then the heat obtained is known as the
Lower Calorific Value.
Relation between Higher and Lower Calorific Value. LCV = HCV – Heat carried away by the steam.
Ques 44: What is mean by Knocking? Give the name of chemical use to prevent knocking.
Ans: In certain circumstances, the rate of oxidation becomes so
great that the last portion of the fuel-air mixture gets ignited
instantaneously, producing an explosive violence, known as knocking. Knocking
result in loss of efficiency.Tera Ethyl Lead (TEL) used as an anti knocking
agent.
Ques45: Explain fractional distillation of crude oil.
Ans: Fractional distillation is the process by
which oil refineries
separate crude
oil into different, more useful hydrocarbon products
based on their relative molecular weights in a distillation tower. This is the
first step in the processing of crude oil, and it is considered to be the main
separation process as it performs the initial rough separation of the
different fuels.[2] The
different components that are separated out during this process are known
as fractions. Fractions that are separated out include gasoline, diesel, kerosene,
and bitumen.[3] Fractional
distillation allows a lot of useful products to be made from crude oil, with
many environmental consequences for the use of those useful products.
fractional distillation
tower, showing where the different fractions will condense.[1] Note that the temperature is higher
at the bottom, so the longer carbon chains will fall out at the bottom, the
shorter carbon chains will go up the column until they hit a temperature at
which they become liquid.
Ques 46: Define Power alcohol, write its advantages and disadvantages.
Ans: Power alcohol is a mixture of 80%
Petrol + 20% Ethanol + Small quantity of Benzene. It is
used for the generation of power.Advantages – i) its cost effective compared to
other biofuel.
Ii)
it does not cause pollution to the environment.the mixture of ethanol and
gasoline minimizes the emission of greenhouse gases. And minimize global
warming.
iii) Easily accessible it is classified as a
renewable energy source.
iv) It minimizes dependence on fossil fuels
disadvantages – i) Requires large piece of
land
ii) Distillation process is not good for
environment
iii) Absorb maximum amount of water from
atmosphere.
iv) pure ethanol is hard to vaporize.
Ques 47: Define Octane number and Cetane number.
Ans:
Octane number---it is a measure of the quality of a petrol expressed as
the percentage of isooctane in
a mixture of
isooctane and n-heptane that gives a fuel with
the same antiknock qualities
as the given petrol.
A gasoline with an octane number of 92 has the same knock as
a mixture of
92% isooctane and 8% heptane.
Cetane number – it is a measure of
the quality of a diesel fuel expressed as
the percentage of cetane in a mixture of
cetane and 1-methylnapthalene of the same quality as the given fuel. A gasoline
with a cetane number of 92 has the same knock as a mixture of
92% cetane and 8% 1-methylnaphthalene.
Ques 48: Define Cracking with example.
Ans: Cracking is the breakdown of a large alkane into smaller,
more useful alkenes. Simply put, hydrocarbon cracking is the
process of breaking a long-chain of hydrocarbons into short ones. This process
requires high temperatures.
The hydrocarbon molecules are broken up in a fairly random way to
produce mixtures of smaller hydrocarbons, some of which have carbon-carbon
double bonds. One possible reaction involving the hydrocarbon C15H32 might
be:
Ques 49: Differentiate Exothermic and Endothermic process.
Ans: Exothermic reactions --- these are reactions or processes that release energy, usually in the form of heat or light. In an exothermic reaction, energy is released because the total energy of the products is less than the total energy of the reactants. For this reason, the change in enthalpy,(delta H) for an exothermic reaction will always be negative.
Endothermic reactions --- these are reactions that require external energy, usually in the form of heat, for the reaction to proceed. Since endothermic reactions draw in heat from their surroundings, they tend to cause their environments to cool down. They are also generally non-spontaneous, since endothermic reactions yield products that are higher in energy than the reactants. As such, the change in enthalpy for an endothermic reaction is always positive.
Examples of Endothermic and Exothermic Processes-----
examples of endothermic processes include:
Dissolving ammonium chloride in water
Cracking alkanes
Nucleosynthesis of elements heavier than nickel in stars
Evaporating liquid water
Melting ice
examples of exothermic processes include:
The thermite reaction
A neutralization reaction (e.g., mixing an acid and a base to
form a salt and water)
Most polymerization reactions
Combustion of a fuel
Respiration
Nuclear fission
Corrosion of metal (an oxidation reaction)
Dissolving an acid in water
Ques 50: Explain first law of thermodynamics.
Ans: The First Law of Thermodynamics states that energy can be
converted from one form to another with the interaction of heat, work and
internal energy, but it neither be created nor destroyed,
under any circumstances. Mathematically, this is represented as
ΔU = q + w
ΔU is
the total change in internal energy of a system,
q is the heat exchanged between a system and its
surroundings, and
w is the work done by or on the system.
Ques : 51 Define Open, Closed and Isolated system.
Ans: If the system allows exchange
of energy and matter,between system and surrounding,
known as Open
system. E.g. = hot water in a open
beaker
If the system allows exchange
of energy only not matter,between system and surrounding,
known as Closed
system. E.g. = hot water in a beaker covered by plate
If the system allows exchange
of neither energy nor matter,between system and surrounding,
known as Isolated
system. E.g. = hot water in a thermos flask.
Ques 52: what is difference between Isothermal and Adiabeticprocess.
|
Ans:Difference Between
Isothermal and Adiabatic process |
|
|
Isothermal |
Adiabatic |
|
Transfer
of heat occurs |
No
Transfer of heat occurs |
|
The
pressure is more at a given volume |
The
pressure is less at a given volume |
|
Temperature
remains constant |
Temperature
changes due to internal system variations. |
|
Heat
can be added or released to the system just to keep the same temperature |
There
is no addition of heat nor heat is released because maintaining constant
temperature doesn’t matter here. |
|
The
transformation is slow |
The
transformation is fast |
Ques 53: Differentiate extensive and intensive
properties.
|
Ans: Difference
between Intensive and Extensive properties |
|
|
INTENSIVE |
EXTENSIVE |
|
Independent
property |
Dependent
property |
|
Size
does not change |
Size
changes |
|
It
cannot be computed |
It
can be computed |
|
Can
be easily identified |
Cannot
be easily identified |
|
Example: melting
point, color, ductility, conductivity, pressure, boiling point, luster,
freezing point, odor, density, etc |
Example: length, mass,
weight, volume |
Ques54 :What do you mean by hard and soft water?
Ans: Rainwater
is considered pure water because it does not contain any salt dissolved in it
though there are dissolved gases present. Water can be classified as hard water
and soft water.
Soft water: It lathers with
soap. Water which is obtained from the rains is soft water. This
water is suitable for household purposes for example laundry and cleaning.
Hard water: It is known as hard water because of
the presence of salts of calcium and magnesium. Hard water does not lather with
soap instead forms a precipitate.
Ques 55: Explain types of hardness of water .
Ans: The hardness of water can be classified into two types:
Temporary Hardness
Permanent Hardness
Temporary Hardness of Water:
The presence of magnesium and calcium bicarbonates in water makes it temporarily hard. In this case, the hardness in water can be removed by boiling the water.
When we boil water the soluble salts of Mg(HCO3)2 is
converted to Mg(OH)2 which is insoluble and hence gets
precipitated and is removed. After filtration, the water we get is soft water.
Permanent Hardness of Water:
When the soluble salts of magnesium and calcium are
present in the form of chlorides and sulfates in water, we call it permanent
hardness because this hardness can not
be removed by boiling.
We can remove this hardness by treating the water with washing soda. Insoluble carbonates are formed when washing soda reacts with the sulfide and chloride salts of magnesium and calcium and thus hard water is converted to soft water.
Ques 56: Write the name of methods by which permanent hardness can be remove.
Ans: 1) Lime soda method
2) Permutit
method
3) Calgon method
4) Ion exchange
method
5) Reverse
osmosis method
Ques 57: Mention the disadvantage of hard water.
Ans: Disadvantages of hard water ----
Linens and clothes look dull and feel rough.
Ugly stains on white porcelain and scale buildup on faucets
Low water pressure from showers due to clogged pipes.
Chalky, white residue or spots appear on dishes.
.webp)
Thanks for the messages.