Short Answers and Questions
Basic Concepts
Chapter No.1
Question:
Define chemistry
Answer:
The branch of chemistry which deals with study of composition, structure, properties and changes of matter and laws and principle that governs these changes is called chemistry
Question:
Define Atomicity
Answer:
The number of atoms
present in molecule is called atomicity. For example; atomicity of glucose is
24 and atomicity of hemoglobin is 10,000
Question:
Why formation of cation is endothermic reaction
Answer:
When an electron is
removed from an atom, energy is required to overcome the force of attraction
between electrons and nucleus, that’s why formation of cation is an endothermic
reaction.
Question:
Why formation of anion is an exothermic reaction
Answer:
When an electron is added
to an atom, energy is released from an atom due to overcome the force of
repulsion between electrons and incoming electron, that’s why formation of
anion is an exothermic reaction
Question:
Define Molecular Ions
Answer:
Molecules carry both
positive and negative charge is called molecular ions
For example CO+, O2-,
Question: How molecular ions are produced
Answer:
Cation molecular ions
are formed by the bombardment of electron beam beta rays alpha rays and X- rays
on the gas molecules
Answer:
Relative atomic mass is
the mass of an atom of an element as compare to the mass of atom of carbon
taken as 12.
Relative atomic masses
are measured in atomic mass unit
Answer:
The atom of same element
having same atomic number but different atomic masses are called isotopes
For example: hydrogen
has three isotopes protium, deuterium and tritium
Answer:
A formula which
shows the simplest whole number ratio between the atoms present in a compound
is called empirical formula
For example:
benzene CH, glucose CH2O
Answer:
The formula of substance
which is based upon actual number of atoms present in a molecule of a compound
is called molecular formula
Example: benzene C6 H6, glucose C6 H12 O
Molecular formula=
n x empirical formula
Answer:
Atomic mass of an element molecular mass of a molecule formula mass of an ionic substance and ionic mass of ionic species when Express in gram is called mole
23 Graham of sodium = 1
mole
18 Graham of water = 1
mole
58.5 gram of sodium chloride = 1 mole
Question: Write basic assumptions for
stoichiometric calculations
Answer:
·
All the reactants are
completely converted into products
·
No side reactions occur
· The reaction must be Irreversible
Question: Write limitation of a chemical
equation
Answer:
·
Chemical equation does
not show the rate of reaction
·
It does not tell about
the condition necessary for reactions
·
The chemical equation
can even be written to describe a chemical change that does not occur
Question: Define Limiting Reactant
Answer:
Reactant which is completely consumed earlier leaving behind the other reactant in excess is called limiting reactant
A limiting reactant:
·
is consumed earlier
·
is in lesser than
stoichiometric amount
·
Limit the chemical
reaction
·
Limit the amount of product
· give least amount of product
Question: Write steps to calculate the limiting reactant
Answer:
·
Calculate the number of
moles from the given amount of reactants
·
Find out the number of
moles of product with the help of balanced chemical equation
·
Identify the reactants
which produces the least amount of product as a limiting reactant
Answer:
The amount of product
calculated from a balanced chemical equation are produced as a result of
chemical reaction is known as yield.
Answer:
Theoretical yield
The amount of product calculated from the
balanced chemical equation is called theoretical yield
Actual yield
It is the maximum amount of product that should be produced according to the balanced chemical equation
Question: Why actual yield is less than
theoretical yield
Answer:
Side reactions, reversible reactions, incomplete
reactions, in experience worker, mechanical loss during separation by, solvent
extraction filtration distillation and crystallization and actual yield maybe
laser due to inefficiency during the washing and drying of crystals
Answer:
23 gram of sodium = 1
mole = 6.02 x 1023 atoms
238 grams of Uranium = 1
mole = 6.02 x 1023 atoms
That’s why both have
equal number of atoms in them
Answer:
One mole of magnesium =
24 gram
One mole of carbon = 12
gram
That’s why magnesium is twice heavier than carbon atom
Question: 180 gram of glucose and 342 grams of
sucrose have same number of molecules but different number of atoms present in
them
Answer:
180 grams of glucose = 1
mole = 6.02 X 1023 molecules
342 grams of sucrose = 1 mole = 6.0 to X 1023 molecules
One mole of glucose C6
H12 O6= 24 atoms
One mole of
sucrose C12 H22 O11= 45 atom
That’s why both have same number of molecules both have different number of atoms in them
Question:
No individual Neon atom in the sample of the element has a mass of 20.18 amu
Answer:
It is the average atomic
mass of different isotopes of different of neon atom in the sample of the
element has the mass of 20.18 amu
Click Here To Download:
