CHAPTER # 1
FUNDAMENTALS OF
CHEMISTRY
Exercise
short questions.
(1)
Define
industrial chemistry and analytical chemistry.
Industrial chemistry can be defined as “The
branch of chemistry which deals with manufacturing of chemical compounds on
commercial scale e.g. preparation of basic chemicals such as
oxygen (O2), chlorine(Cl2), ammonia(NH3) caustic
soda (NaOH) etc.
Whereas , analytical chemistry is the branch
of chemistry which deals with separation and analysis of a sample to identify
its components. The separation is carried out either for qualitative
(composition of chemical species) or quantitative (amount of each component in
the sample)
(2)
How can you
differentiate between organic and
inorganic chemistry.
Sr. No
|
Organic Chemistry
|
Inorganic Chemistry
|
1
|
The branch
of chemistry which deals with study of covalent compounds of carbon,
hydrogen(hydrocarbons)and
their derivatives.
|
The branch
of chemistry Which deals with study of all elements ,their compounds and
their derivatives except carbon and
hydrogen (hydrocarbons).
|
2
|
Organic
Chemistry may be natural or artificially synthesized. An organic chemist also
determine the structure of organic compounds.
|
This
branch has applications in chemical industry like glass ,cement , ceramics
etc.
|
(3)
Give the
scope of biochemistry.
Biochemistry deals with study of structure ,
composition and chemical reaction of substances taking place in living
organisms. Reactions which are carried out in living organism follow the laws
of chemistry. It deals with all the chemical processes taking place in living
organisms e.g. synthesis and metabolism of biomolecules like protein,
carbohydrates, lipids and DNA . It has applications in fields of medicine and
food science etc.
(4)
How does
homogeneous mixture differ from heterogeneous mixture.
Sr.No
|
Homogeneous mixture
|
Heterogeneous mixture
|
1
|
A mixture which has throughout uniform composition is called
homogeneous mixture.
|
A mixture which has throughout non-uniform composition is called
heterogeneous mixture.
|
2
|
Examples : Air ,ice cream,etc.
|
Examples: Wood, soil, rock
etc
|
3
(5)
What is
relative atomic mass ? How is it related to gram?
Relative atomic mass of elements is defined
as “The average mass of the atoms of an element as compared to 1/12th (one-twelfth)
the mass of an atom of carbon 12 isotope .” The unit of relative atomic
mass is called amu (atomic mass unit ) and it is equal to
1 amu = 1.66 * 10 -24 gram
 |
(6)
Define
empirical formula with example.
A formula
which shows the simplest whole number ratio of atoms present in a compound is
called empirical formula. For example , the empirical formula of benzene (C6H6)
is CH , while glucose (C6H12O6) has CH2O.
(7)
State three
reasons what do you think air is a mixture and water a compound ?
Sr.No
|
Air is a mixture
|
Water as a compound
|
1
|
Air is formed by simple mixing of N2, O2,
CO2 and noble gases.
|
Water is formed by the chemical combination of H2 and
O2.
|
2
|
It can be separated into its components by physical methods.
|
It cannot be separated into H2 and O2 by
simple physical methods.
|
3
|
It does not have fixed composition.
|
It has fixed composition.
|
4
|
It does not have chemical
formula.
|
It has a chemical formula (H2O).
|
5
|
It does not have fixed melting
point.
|
It has sharp and fixed melting
point i.e. 100o C.
|
(8)
Explain why
are hydrogen and oxygen considered elements whereas water as a compounds?
Sr.No
|
H2 and O2
as an element
|
Water as a compound
|
1
|
Both hydrogen and oxygen can’t be chemically broken down into
simpler substances.
|
Chemically water (H2O) can be broken-down into H2
and O2.
|
2
|
Both H2 and O2 are identified
by symbols.
|
It is identified by chemical formula like water (H2O).
|
3
|
Both H2 and O2 are formed by same type of
atoms and have fixed atomic number , so both are elements.
|
It is formed by the chemical combination of both H2
and O2 , so it is a compound.
|
4
|
Both H2 and O2 have property of valency.
|
It does not have property of valency.
|
(9)
What is the
significance of symbol of an element?
The
significance of the symbol of an element is given as following:
(a)
A symbol is used to replace the name of an element.
(b)
A symbol is used to represent the one atom of an element.
(c)
A symbol for the elements are the alphabet for the language of
chemistry.
(d)
A symbol is a short hand representation of an element.
(10)
State the reason : soft drink is a mixture
and water is a compound.
5
Sr.No
|
Soft drink as a mixture
|
Water as a compound
|
1
|
It is a mixture of sugar, water, carbon dioxide , etc
|
Water is formed by the chemical combination of H2 and
O2.
|
2
|
It can be separated into its components by physical methods.
|
It cannot be separated into H2 and O2 by
simple physical methods.
|
3
|
It does not have fixed composition.
|
It has fixed composition.
|
4
|
It does not have chemical formula.
|
It has a chemical formula (H2O).
|
5
|
The components retain their own identity.
|
The components lost their own identity.
|
(11)
Classify the following into elements, compound or mixture.
(a).
He and H2: Both are
elements.
(b). CO and Co: CO is a compound while Co is an element.
(c).
Water and Milk: Water is a compound
while milk is a mixture.
(d). Gold and Brass: Gold is
element while Brass is a mixture. (Cu+Zn)
(e). Iron and Steel: Iron is an element while Steel is a mixture.
6
(12) Define atomic mass. Why is it needed?
It can be
defined as “The mass equal to 1/12th(one-twelfth) of
Mass of an atom of carbon (carbon-12).Because mass of an atom cannot be
determined precisely. So we sue atomic mass unit(amu).
(13) State the nature and name of substance formed
by combining the following.
(a) .Zinc + Copper:
Zinc + copper Brass (Mixture)
(b). Water + Sugar:
Water + Sugar Mixture (also an aqueous solution )
(c). Aluminium + Sulphur:
Aluminum + Sulphur Aluminum
Sulphide. (Compound ).
(d). Iron + Chromium + Nickle:
Iron+ Chromium + Nickle Steel (compound ). Steel is also
called Nichrome.
(14) Differentiate between molecular mass and
formula mass, which of the followings have molecular formula?
H2O,NaCl, KI, H2SO4
OR
7
Differentiate between molecular
mass and formula mass.
Sr.No
|
Molecular Mass
|
Formula Mass
|
1
|
The sum of
atomic masses of all the atoms present in a molecule of molecular compound is
called molecular mass.
|
The sum of
atomic masses of all the atoms present in one formula unit of ionic compound
is called formula mass.
|
2
|
Here H2O and H2SO4 are
molecular formulas
|
Here NaCl and KI are formula units.
|
(15) Which
one has more atoms:10g of Al or 10g of Fe?
Number of
atoms (Al)= Mass in gram / Molar mass * NA
Number of atoms (Al)= 10/ 27 * 6.02* 1023
Number of atoms (Al)=2.23 * 10 23
Number of atoms (Fe) = Mass in gram / Molar mass * NA
Number of atoms (Fe) =10/ 56 * 6.02*1023
Number of
atoms (Fe) = 1.075 * 1023
Number of atoms (Fe)=
|
(16) Which one has more molecules:9 g of Water or 9 g of Sugar?
Number of molecules (Water) =
Mass in gram/Molar mass * NA
Number of molecules (Water) = 9/18 * 6.02 *1023
8
Number of molecules (Water) =3.01 * 1023 molecules
Number of molecules (Sugar) =
Mass in gram/Molar mass * NA
Number of molecules (Sugar) =9/342 * 6.02 * 1023
Number of molecules (Sugar) =1.58 * 1022 molecules
|
 |
|||
 |
(17) Which one has more formula units:1g of NaCl or 1g of KCl?
Number of formula units (NaCl)=Mass in gram/Molar mass *NA
Number of formula units (NaCl) = 1/58.5 * 6.02*1023
Number of formula units (NaCl) = 1.03 * 10 23
Number of formula units (KCl) =Mass in gram/Molar mass*NA
Number of formula units (KCl) = 1/74.5*1023
Number of formula units (KCl) = 0.081 * 1023 formula units
9
(18)
Differentiate between homo atomic and hetero atomic molecules with example.
Sr.No
|
Homo atomic molecules
|
Hetero atomic molecules
|
1
|
A molecule
containing same type of atoms is called homo atomic molecule.
|
A molecule
containing different type of atoms is called hetero atomic molecules.
|
2
|
Example :
Hydrogen(H2), Sulphur(S8), Ozone(O3),
Oxygen(O2) etc.
|
Example :
Carbon dioxide (CO2), Water(H2O), ammonia (NH3),
carbon monoxide(CO)etc.
|
(19) In
which one of the followings the number of hydrogen atoms is more?
2 moles of HCl or 1 mole of NH3
1 mole of HCl contains = 1 mole of hydrogen
atoms
chemistry chapter 1, chemistry chapter1, short questions chapter 1 chemistry,
Hence,
2 moles of HCl contains= 2 moles of hydrogen atoms
Where AS
1 mole of NH3 contains
= 3 moles of hydrogen atoms ,It proves that one mole of NH3 has more number of hydrogen
atoms.
Very much helpful notes.i want u to post notes of all chapters of science subject.keep working with same spirit
ReplyDelete