Chapter 01 Exercise Chemistry
Chapter 01 Exercise Chemistry
Chapter 01 Exercise Chemistry
CHAPTER 01
STOICHIOMETRY
EXERCISE SOLVED
( SHORT QUESTIONS )
Ans ;- Stoichiometry :- The branch of chemistry which deals with discuss about quantitative relationship
between amount of reactant and product shown by a balanced chemical equation .
Exponential Notation:- It is also known as scientific notation , is a way of representing numbers that are
very large or very small in a concise format . In exponential notation , a number is expressed as the
product of a coefficient and a power of 10 .
Molar Volume :- The amount of a gas in one mole and it is kept under STP . then its volume will be
22.4dm^3 . mass of a gas can be converted into volume and volume can be converted into mass .
=> One mole of any gas at STP = 22.4dm^3 = 6.02 x 10^23 molecules .
(1) 3652
(2) 0.0231
(3) 0.000072
=> 0.00326
=> 192
=> 102000
Q;04 ;- Define rounding off data , give various rules of rounding off data .
Ans ;- To reduce a number upto desired significant figures and adjust the last reported digit is known as
rounding off data .
(1) If digit to be dropped is greater than 5 , then add 1 to the digit to be retained .
(2) If the digit to be dropped is less than 5 , then simply drop it without changing proceeding number .
( LONG QUESTIONS )
Q:-01 ;- Define theoretical yield , actual yield and percen yield . Why the practical yield is less than
theoretical yield ?
Ans :- Theoretical Yield :- The product which is obtained with the help of calculations ( before Reaction ) .
Practical yield :- The product which is obtained by performing the chemical reaction in the laboratory or
industry is called practical yield . Practical yield in a reaction is almost always less than the theoretical
yield , primarily because losses of substance involved may occur anywhere in an experiment . Of course ,
a true actual yield can never be greater than the true theoretical yield in a reaction , the possible
occurence in reaction .
% Yield :- the yield which is obtained by dividing the practical yield by theoretical yield and multipled by
100 .
Ans ;- Mole and Avogadro's number are both concepts used in chemistry to describe the quantity of
particles such as atoms , molecules or ions .
MOLE ;- the mole is a unit of measurement used to express the amount of a substance . one mole of any
substance contains same number of particle which is approximately 6.02 x 10^23 particles .
In mathematical terms :
N = n x NA
=> MOle and avogadro's number are closely related concepts used to quantify the amount of substance
in chemistry , with Avogadro's number providing a specific count of particles in one mole of substance .
Q;03;- What is meant by avogadro's number ? Explain the concept of mole with the help of avogadro's
number ?
Ans:- Avogadro's number is a fundamental constant in chemistry that represents the number of particles
( atoms , molecules , ions etc ) present in one mole of substance . It is denoted by the symbol NA and has
a value of approximately 6.02 x 10^23 particles per mole .
=> Avogadro's number provides a specific count of particles in one mole of a substance . Therefore , it is
used as a conversion factor to relate the number of particles to the amount of subastance in mole . this
allows chemists to quantify substances based on their constituent particles .
Q;04;- What is limiting reactant ? how does it control the amount of product formed in a chemical
reaction ?
Ans ;- The reaction which is present in similar quantity as compared to its stoichiometric amount or
required amount . Consumed earlier , will gave a smaller quantity of product control or stop the reaction
is called limiting reactant .
=> the limiting reactant controlss the amount of product formed because it determines how much
product can be produced before reaction stops . Any excess reactants beyond the limiting reactant donot
contribute to formation of additiona product