Tag: enzymes and catalysts

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Questions Related to enzymes and catalysts

Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

In a chemical reaction, the solid catalyst function as:

  1. Adsorbent

  2. Adsorbate

  3. Micelle

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In heterogeneous catalysis where a solid catalyst is used, reactant molecules in gaseous or liquid phase accumulate on the surface of the solid catalyst. This surface phenomenon is known as adsorption.

Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

Removal of adsorbate from the surface of adsorbent is called _____.

  1. desorption

  2. absorbation

  3. adsorbation

  4. none
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Removal of adsorbate from the surface of adsorbent is called desorption.
It is the reverse of adsorption. 

For example, when hydrogen gas is adsorbed on the surface of Pt and the temperature is raised or pressure is lowered, some of the hydrogen gas escapes from the surface of Pt. This is known as desorption.

Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

The name catalysis was given by: 

  1. Rutherford

  2. Langmuir

  3. Graham

  4. Berzelius
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The word catalysis was first used by Berzelius in 1836 to describe a number of experimental reactions. Catalysis is defined as a phenomenon in which the presence of a foreign compound in a reaction can accelerate its rate without being used  in that reaction. These foreign substances are called as a catalyst.

Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

According to adsorption theory of catalysis, the reaction rate increases, because:

  1. Adsorption produces heat which increases the rate of reaction

  2. In the process of adsorption, the kinetic energy of the molecules increases

  3. The concentration of reactants at the active centres becomes high due to adsorption

  4. The activation energy of the reaction becomes high due to adsorption
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Adsorption increases the reaction rate by concentrating reactant molecules on the surface of the catalyst, which increases the frequency of effective collisions. This is the fundamental principle of surface catalysis.

Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

In which of the following processes, a catalyst is not used? 

  1. Haber's process and Deacon's process

  2. Deacon's process and Solvay process

  3. Solvay process and Lead chamber process

  4. None of these can proceed without catalyst
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Haber's process catalyst is finely divided iron

Deacon's process catalyst is copper chloride

Solvay process catalyst is ammonia-soda

Lead chamber process catalyst is platimnum.

So in the all above process is catalyst is used.

Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

According to adsorption theory of catalysis, the speed of reaction increases because:

  1. the concentration of the reactant molecules at the active centres of the catalyst becomes high due to adsorption

  2. in the process of adsorption, the activation energy of the molecules becomes large

  3. adsorption produces heat which increases the speed of the reaction

  4. adsorption lowers the activation energy of the reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to adsorption theory of catalysis, the speed of reaction increases because the concentration of the reactant molecules at the active centres of catalyst becomes high due to adsorption.

Hence option A is correct.

Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

According to the adsorption theory of catalysis,the speed of the reaction increase because :

  1. The concentration of reactant molecules at the active centers of the catalyst becomes high due to adsorption

  2. In the process of adsorption, the activation energy of the molecules becomes large

  3. Adsorption produces heat which increases the speed of the reaction

  4. Adsorption lowers the activation energy of the reaction.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The correct answer is $D$ . In the presence of catalyst the speed of reaction increases since the activation energy gets reduced and hence the rate of adsorption increases.

Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

Chlorophyll, the green colouring matter in plants helps the process of photosynthesis by:

  1. acting as a catalyst

  2. converting soil into carbohydrates

  3. reacting with carbon dioxide

  4. fixing soil nitrogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Chlorophyll plays a vital role by absorbing sunlight of a range of wavelengths, primarily blue and red. It is a catalyst for photosynthesis - increasing the speed of the reaction by taking part in it but remaining unchanged at the end.
Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

Match the reaction of Column - I with the catalysts in Column - II:

Column - I(Reaction) Column - II(Catalyst)
(a) $2KClO _3(s) \rightarrow 2KCl(s) +3O _2(g)$ (p) $Al _2O _3$
(b) $ 2SO _2(g) +O _2(g) \rightarrow 2SO _3(g)$ (q) $Pt$
(c) $2H _2O _2(l) \rightarrow 2H _2O(l) +O _2(g)$ (r) $V _2O _5$
(d) $ N _2(g) + 3H _2 (g) \rightarrow 2NH _3 (g)$ (s) $MnO _2$
  1. $a\rightarrow s,b\rightarrow r,c\rightarrow s,d\rightarrow p\ \& \ q$
  2. $a\rightarrow p,b\rightarrow r,c\rightarrow s,d\rightarrow p\ \& \ s$
  3. $a\rightarrow q,b\rightarrow r,c\rightarrow s,d\rightarrow q$
  4. $a\rightarrow s,b\rightarrow r,c\rightarrow q,d\rightarrow p\ \& \ q$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

a)  For $KClO _3$ decomposition Manganeese(IV) oxide is used as catalyst at an elevated temparature of 150 degree given by the formula $MnO _2$.


b) The catalyst that promotes the $SO _2$ oxidation at temparature of 500 degree where $SO _2$ is thermodynamically efficient is vanadium pentoxide given by $V _2O _5$.


c) The catalyst that provides alternative way with low activation energy  for decomposition of $H _2O _2$ is $MnO _2$.

d) Synthesis of Ammonia by Haber process uses $Pt$ and $Al _2O _3$ as a compromise catalysts in place of $Fe$.

Option A is correctt.