Tag: chemistry

Questions Related to chemistry

Nylon is a well-known polymer used in fabrics and motor tyres. Nylon$-6,6$ is made from hexamethylenetetramine (having six methyl groups) and :

synthetic polyamides polymerisation chemistry

  1. adipic acid, a six-carbon chain fatty acid

  2. sulphurous acid with six atoms of various elements

  3. sulphure hexafluoride with six fluorine atoms

  4. cobalt hexamine cation with six ammonia ligands

Show answer
Correct Option: A
Explanation:
Nylon is a generic name for a synthetic linear polymer with repeating amide groups $(−NH−CO−)$ which is used in the manufacture of textile fibres. Carothers produced Nylon-66 by the condensation reaction of adipic acid (a dicarboxylic acid with 6 carbon atoms) and hexamethylene-di-amine (a diamine with 6 carbon atoms) give the $[−NH−{(C{H} _{2})} _{6}−NH−CO{(C{H} _{2})} _{4}−CO−]$ repeating unit. Nylon revolutionised the textile industry and was the forerunner for many of today's modern, synthetic fabrics.

Which of the following polymers are used as fibre?

synthetic polyamides polymerisation chemistry

  1. Nylon

  2. Polytetrafluoroethane

  3. Terylene

  4. Buna-S

Show answer
Correct Option: A
Explanation:

Nylon is used as fiber because, it is very important substitute of silk, it's other properties is elasticity, strength and resistance for mildew.

So the correct option is [A].

Polymer which has amide linkage is:

synthetic polyamides polymerisation chemistry

  1. nylon-$6,6$

  2. terylene

  3. teflon

  4. bakelite

Show answer
Correct Option: A
Explanation:

Polyamides have the amide linkage.

Example- Nylon 6-6, Nylon 6
Nylon 6, 6 is used in making sheets, bristles for brushes and in the textile industry.

The correct option is [A].

The ratio between the $\pi -$ bonds in the monomers of N-vinylpyrolidone and perlon-L is:

synthetic polyamides polymerisation chemistry

  1. $2 : 1$

  2. $1 : 2$

  3. $3: 2$

  4. $2 : 3$

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Correct Option: A

Which of the following polymers does not have vinylic monomer units?

synthetic polyamides polymerisation chemistry

  1. Acrilan

  2. Nylon

  3. Polystyrene

  4. Neoprene

Show answer
Correct Option: B
Explanation:
 Acrilan  $(-CH _2=CHCN-) _n$
 Polystyrene  $(-C _6H _5-CH _2=CH _2-) _n$
 Neoprene  $(-CH _2=CHCl-) _n$
 Nylon  $(Hexa methylene \,di amine + adipic\,acid) _n$

Only nylon does not have vinylic monomer units.

So the correct option is [B].

The polymer formed by the condensation of hexamethylenediamine and adipic acid is

synthetic polyamides polymerisation chemistry

  1. Teflon

  2. Bakelite

  3. Dacron

  4. Nylon-66

Show answer
Correct Option: D
Explanation:

The polymer formed by the condensation of hexamethylenediamine $\displaystyle (H _2N-(CH _2) _6-NH _2)$ and adipic acid $\displaystyle (HOOC-(CH _2) _4-COOH)$ is Nylon-66.
$\displaystyle H _2N-(CH _2) _6-NH _2+HOOC-(CH _2) _4-COOH  \xrightarrow {\Delta} H _3N^+-(CH _2) _6-NH _3^+O^-OC-(CH _2) _4-COO^-$


$\displaystyle nH _3N^+-(CH _2) _6-NH _3^+O^-OC-(CH _2) _4-COO^-\xrightarrow [-H _2O]{\Delta} \underset{\text{Nylon} 6,6}{[HN-(CH _2) _6-NH \underset {\displaystyle  \underset {\displaystyle \text {O }}{||} }{C}-(CH _2) _4- \underset {\displaystyle  \underset {\displaystyle \text {O }}{||} }{C}] _n}$

Fill up the following with suitable terms.

(i) Activation energy $=$ Threshold energy $-$ ____.

(ii) Half-life period of zero order reaction $=$ __.

(iii) Average rate of reaction $=$ _.

(iv) Instantaneous rate of reaction $=$ ___.

chemistry chemical kinetics introduction to chemical kinetics understanding chemical kinetics rate of chemical reaction

  1. Potential energy, $\dfrac {0.693}{k}, \dfrac {dx}{dt}, \dfrac {\triangle [A]}{\triangle t}$

  2. Energy of reactants, $\dfrac {1}{k}, \dfrac {\triangle [A]}{\triangle t}, \dfrac {dx}{dt}$

  3. Energy of reaction, $\dfrac {\log k}{t}, \dfrac {\triangle [A]}{\triangle t}, \dfrac {dx}{dt}$

  4. Average kinetic energy of reactants, $\dfrac {a}{2k}, \dfrac {\triangle [A]}{\triangle t}, \dfrac {dx}{dt}$

Show answer
Correct Option: D
Explanation:
a) Activation energy = Threshold energy$-$ the Average kinetic energy of molecules(by definition)

b) half-life of a zero order reaction = ${ t } _{ \frac { 1 }{ 2 }  } =\frac { a }{ 2k } $

c) Average rate of reaction = $\dfrac {\displaystyle \text{ Total change concentration reactants }}{ \displaystyle \text{Total time taken} }$  = $\dfrac { \triangle \left[ A \right]  }{ \triangle t }$

d) Instantaneous rate of reaction =$ \dfrac { \displaystyle \text {Instantaneous change in concentration} }{\displaystyle \text { Instantaneous  time} } $=$\dfrac { dx }{ dt } $                    

Chemical kinetics a branch of physical chemistry deals with:

chemistry chemical kinetics introduction to chemical kinetics understanding chemical kinetics rate of chemical reaction

  1. structure of molecules

  2. heat changes in a reaction

  3. physical changes in a reaction

  4. rate of reactions

Show answer
Correct Option: D
Explanation:
Chemical kinetics is branch of physical chemistry that is concerned with understanding the rates of chemical reactions.

Structures and physical changes are deal in solid state and while studying liquids.

Thermochemistry deals with energy changes in chemical reactions.


If reaction A and B are given with Same temperature and same concentration but rate of $A$ is double than $B$. Pre exponential factor is same for both the reaction then difference in activation energy $E _{A} - E _{B}$ is?

chemistry chemical kinetics introduction to chemical kinetics understanding chemical kinetics rate of chemical reaction

  1. $-RT\ ln2$

  2. $RT\ ln2$

  3. $2RT$

  4. $\dfrac {RT}{2}$

Show answer
Correct Option: A
Explanation:

$\dfrac {r _{A}}{r _{B}} = \dfrac {A _{1}e^{\dfrac {-E _{A}}{RT}}}{A _{2}e^{\dfrac {-E _{B}}{RT}}}$
$\dfrac {2}{1} = \dfrac {e^{\dfrac {-E _{A}}{RT}}}{e^{\dfrac {-E _{B}}{RT}}}$
$ln2 = E _{B} - E _{A} / RT$
$E _{B} - E _{A} = RT\ ln2$
$E _{A} - E _{B} = -RT\ ln2$.

Which of the following theory is not related to the chemical kinetics?

chemistry chemical kinetics introduction to chemical kinetics understanding chemical kinetics rate of chemical reaction

  1. Collision theory

  2. Absolute theory

  3. Absolute reaction rate

  4. VSEPR theory

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Correct Option: D
Explanation:

Valence shell electron pair repulsion (VSEPR) theory is a model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms.

It's not related to the chemical kinetics.