Catalysis MCQ Quiz in मल्याळम - Objective Question with Answer for Catalysis - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

The correct answer is Esterification.

Key Points

• Sulfuric Acid:
  • It ​is a highly corrosive, clear, colourless, odourless, strong mineral acid with the formula H₂SO₄.
  • It is a strong acid with hygroscopic(moisture absorbing) and oxidizing properties.
  • It is used in the process of esterification which involves combining an organic acid (RCOOH) with an alcohol (ROH) to form an ester (RCOOR) and water.
    • It is a known catalyst for esterification processes and it plays a dual role:
      • It works to speed up the rate of the reaction. ​
      • It acts as a dehydrating agent, thereby forcing the equilibrium reaction to the right.
        • ​This results in a greater yield of the required ester.
  • ​It is also called the "oil of vitriol" due to its oily appearance and its presence in vitreous or glassy substances such as ferrous sulphate and alum.
  • ​​Concentrated Sulfuric acid is used in
    • ​manufacture of fertilizers
    • lead-acid batteries
    • mineral processing
    • wastewater processing​

Additional Information

• Hydrogenation
  • It is a chemical reaction between molecular hydrogen and other compounds and elements.
  • It is used in many applications such as the food industry, petrochemical industry and pharmaceutical manufacturing industry.
• Pasteurization
  • It is a method of killing harmful bacteria and extending the shelf life of commonly consumed beverages. 
  • In the case of milk, the process involves the heating of every particle of milk or milk product in properly designed and operated equipment with the specified pasteurization time-temperature combinations.

The correct answer is Catalyst changes the equilibrium constant of a reaction.

Key Points

• Equilibrium constant:
  • It is the ratio between the amount of reactant and the amount of product which is used to determine chemical behaviour.
  • It is the condition of a system when the concentration of the reactant and the concentration of the product do not fluctuate over time and the system does not exhibit any additional changes in attributes.
  • It is achieved when the rate of the forward reaction is equal to the rate of the reverse reaction.
  • A catalyst does not change the equilibrium constant but:
    • ​It speeds up a reaction.
    • It equally speeds up the forward as well as the reverse reaction.
    • This results in the reaction reaching its equilibrium faster.

​

Additional Information

• Catalyst does not start a reaction but it only speeds up the reaction which otherwise would happen at a slower pace.
• Because coenzymes are the molecules that bind to and activate enzymes, they can improve the activity of enzymes.
• Biochemical reactions are mostly catalysed by enzymes as they are specific to the substrate and binding site.

The correct answer is the Activation energy

Key Points

• When a catalyst is utilised in a reaction, the activation energy changes. 
• Activation energy is the minimum amount of energy that must be provided for compounds to result in a chemical reaction. 
• The activation energy of a reaction is measured in joules per mole, kilojoules per mole or kilocalories per mole.

Additional Information

• The heat of the reaction depends on the reactants and the products formed.
• The product or rate of reaction depends on the decreasing concentration of reactants or the change in concentration of the reactant in unit time.
• The equilibrium constant depends on temperature and is independent of the actual quantities of reactants and products, the presence of a catalyst and the presence of inert material. 

The correct answer is Optimum temperature

Key Points

• An optimum temperature is a temperature at which a catalyst is most effective.
• Biochemical catalysts are unique to certain types of reactions, which means they cannot be used for multiple responses.
• Regardless of the temperature, the activity of the biochemical catalysts declines.

 Additional Information

• Enzymes are good examples of biochemical catalysts. 
  • Each enzyme has a temperature range in which a maximal rate of reaction is achieved. 
  • The maximum is known as the temperature optimum of the enzyme.
  • The optimum temperature for most enzymes is about 98.6 degrees Fahrenheit ( 37 degrees Celsius). 
• Room temperature is a comfortable ambient temperature, generally taken as about 20⁰C. 
• The critical temperature is the highest temperature at which the substance can exist as a liquid.
  • At temperatures above the critical temperature, the substance can no longer be liquified, regardless of the amount of pressure applied.
• Absolute temperature is measured using the Kelvin scale where zero is absolute zero. 
  • The zero point is the temperature at which particles of matter have their minimum motion and can become colder. 

The correct answer is Catalyst changes the equilibrium constant of a reaction.

Key Points

• Equilibrium constant:
  • It is the ratio between the amount of reactant and the amount of product which is used to determine chemical behaviour.
  • It is the condition of a system when the concentration of the reactant and the concentration of the product do not fluctuate over time and the system does not exhibit any additional changes in attributes.
  • It is achieved when the rate of the forward reaction is equal to the rate of the reverse reaction.
  • A catalyst does not change the equilibrium constant but:
    • ​It speeds up a reaction.
    • It equally speeds up the forward as well as the reverse reaction.
    • This results in the reaction reaching its equilibrium faster.

​

Additional Information

• Catalyst does not start a reaction but it only speeds up the reaction which otherwise would happen at a slower pace.
• Because coenzymes are the molecules that bind to and activate enzymes, they can improve the activity of enzymes.
• Biochemical reactions are mostly catalysed by enzymes as they are specific to the substrate and binding site.

Concept:

• A catalyst is a substance that can be added to a reaction to enhance the reaction rate without getting consumed in the process.
• Catalysts typically speed up a reaction by lowering the activation energy or changing the reaction mechanism.
• Enzymes are proteins that act as catalysts in biochemical reactions.
• A stoichiometric amount of one reactant can mean the amount that will react completely with a given amount of another reactant, leaving no excess of either one.
• Catalyst does not take part in balancing the chemical reaction hence catalysts are not required in Stoichiometric amounts.
• Most common catalysts are - Aluminosilicates, Iron, Vanadium, Nickel, Platinum + Alumina.

​

​Shape selective catalysts:

• Some catalysis reactions depend upon the pore size of the reactant and the shape of catalyst used.
• The pore size and shape of catalysts is similar to the shape and size of the reactants then they can fit into each other and the reaction takes place.
• Zeolites are for example are shape-selective catalysts. They can catalyze only selective reactions.
• The pore size of Zeolites do not permit all transition state complex to pass through it, thus becomes selective in nature.
• Zeolites are large network of aluminosilicates having the network type Al-O-Si. Molecules like water and alkali metals are trapped inside the pores of the networks.

Explanation:

• Zeolites, a shape selective catalyst or HZSM-5 are the catalysts used in conversion of alcohols to gasoline.
• The temperature range is 300-400^oC.
• The alcohols first undergo dehydration to give unsaturated alkenes.
• The alkenes are then converted to higher alkenes via hydrogenation.
• The catalyst used in Haber's process synstesis of ammonia is Fe.
• It increases the rate of reaction between nitrogen and hydrogen.
• Finely divides solid Fe provides a surface for the reaction to occur.
• Gases nitrogen and hydrogen get adsorbed on the catalyst surface, a reaction occurs, and then the products diffuse out.
• catalysts used for synthesis of methanol from CO and H2 are copper and nickel.
• The catalyst used in polymerisation of ethelene is Zeigler-Natta catalyst.

Hence, a shape selective catalyst used in conversion of alcohol to gasoline.

Explanation:
Hydrogenation of unsaturated oils

• Unsaturated vegetable oils are liquid at room temperature. 
• They can be hardened by reacting them with hydrogen in the presence of a Nickel(Ni) catalyst at about 60^o C. 
• This is called hydrogenation.
• The hydrogen adds to the double-bonded carbons.

The catalyst used during the Hydrogenation of Oils is Nickel. 

Concept:

• A catalyst is a substance that can be added to a reaction to enhance the reaction rate without getting consumed in the process.
• Catalysts typically speed up a reaction by lowering the activation energy or changing the reaction mechanism.
• Enzymes are proteins that act as catalysts in biochemical reactions.
• A stoichiometric amount of one reactant can mean the amount that will react completely with a given amount of another reactant, leaving no excess of either one.
• Catalyst does not take part in balancing the chemical reaction hence catalysts are not required in Stoichiometric amounts.
• The most common catalysts are - Aluminosilicates, Iron, Vanadium, Nickel, Platinum + Alumina.

​

Explanation:
Contacts Process

• Sulphuric acid is prepared via the contact's process which involves the following steps:
• Preparation of sulphur dioxide: In this step. sulphur burns in air or is oxidized to produce sulphur dioxide gas by the reaction:

S + O₂ → SO₂

• Oxidation of sulphur dioxide to sulphur trioxide: In the second step the following reaction takes place:

SO2 + O2 → SO3 ​

• Oxidation of SO2 to SO3 is an exothermic process and releases heat.
• The process occurs with the help of catalyst vanadium pentoxide V₂O₅.
• Formation of oleum: Sulphur trioxide is then dissolved in 94% H₂SO₄ solution to prepare oleum H₂S₃O₇ which is also called fuming sulphuric acid.
• The last step is the dilution of oleum to give sulphuric acid.

The catalyst thus used for the reaction SO2 + O2 → SO3 in Contact's Process is Vanadium pentoxide.

Additional Information

• Fe acts as a catalyst in Haber's Process and Mo acts as a Promoter. 

The correct answer is Catalyst affects forward and backward reactions to the same extent.

Key Points

• A reaction where the reactants and products react together to give the reactants back is a reversible reaction.
• catalyst is a substance that can be added to a reaction to increasing the reaction rate without getting consumed in the process.

Additional Information

• The process of increasing the rate of a chemical reaction by adding a substance known as a catalyst.
• Catalysts are not consumed in the catalyzed reaction.
• On the basis of nature and the physical state of a substance in the chemical reaction, catalysis is of three types:
  • Homogeneous catalysis.
  • Heterogeneous catalysis.
  • Autocatalysis.
• A catalyst can be either solid, liquid, or gaseous catalysts
• The reacting substances in a reaction and catalyst in that reaction are not in the same state of matter is called Heterogeneous Reaction. 
• Enzymes are proteins that act as catalysts in biochemical reactions