Surface Chemistry Test

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Surface Chemistry Test - 14

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Weekly Quiz Competition

Question 1
1 / -0

The process of passing of a precipitate into colloidal solution, on adding an electrolyte is called:

A
dialysis

B
peptization

C
electrophoresis

D
electrosmosis

Solution

The process of formation or conversion of a precipitate into a colloidal solution is called peptisation.
Question 2
1 / -0

Which of the following catalyst is used in contact process for manufacture of $$H_{2}SO_{4}$$?

A
Oxides of nitrogen

B
$$V_{2}O_{5}$$

C
$$Fe_{2}O_{3}$$

D
Platinised asbestos

Solution

Vanadium (V) Oxide, $$V_2O_5$$ is used as catalyst in this reaction. It increases the rate of the reaction, thus reducing the need for a high temperature.
Question 3
1 / -0

The process of making colloidal solution from a precipitate is called ________.

A
coagulation

B
vulcanization

C
peptization

D
flocculation

Solution

Peptization is the process responsible for the formation of stable dispersion of colloidal particles in a dispersion medium.
Question 4
1 / -0

The role of metal written on arrows in the given chemical reactions is :

A
catalyst

B
oxidising agent

C
reducing agent

D
dehydrating agent

Solution

1) Ni or Pd is used as a catalyst in the hydrogenation of alkenes to form alkanes.

2) Conc. sulfuric acid is used as catalyst in the neutralization reaction of an acid with alcohol to form esters.

3) Alk. potassium permanganate acts as a strong oxidising agent for converting alcohols to their respective acids.

Hence the correct option is A.
Question 5
1 / -0

The magnitude of ______________ decreases in the presence of a catalyst.

A
activation energy

B
dissociation energy

C
energy barrier

D
intermolecular forces

Solution

In the presence of a catalyst, less free energy is required to reach the transition state. Catalyzed reactions have a lower activation energy.
Question 6
1 / -0

Which of the following statement is incorrect?

A
Enzymes are in colloidal state

B
Enzymes are catalysts

C
Enzymes can catalyze any reaction

D
Urease is an enzyme

Solution

Enzymes are biological catalyst. They may or may not work in all reactions.
Question 7
1 / -0

Which one of the following is an example of homogeneous catalysis?

A
Haber's process of synthesis of ammonia

B
Catalytic conversion of $$SO_{2}$$ to $$SO_{3}$$ in Contact process

C
Catalytic hydrogenation of oils

D
Acid hydrolysis of methyl acetate

Solution

Hint: Homogenous catalysts are those in which the catalyst is in the same phase as the reactants and products.

Explanation:

A)  Haber's process: It combines nitrogen from the air with hydrogen derived mainly from natural gas (methane) into ammonia using Iron oxide catalyst at higher temperature and pressure. The reaction is shown as;
$$N_{2(g)} +3H_{2(g)} \xrightarrow{FeO_{(s)}} 2NH_{3(g)}$$

Here, Catalyst is in Solid-phase while reactants are in gases phases. So, it is an example of heterogeneous catalysis.

B) Contact process: It involves the following steps:
1. makes sulfur dioxide by burning sulfur in excess of air/oxygen.
2. converts the sulfur dioxide into sulfur trioxide in the presence of a catalyst vanadium pentoxide ($$V_2O_5$$)
Reaction is shown as;
$$SO_{2(g)} + 0.5O_{2(g)} \xrightarrow{V_2O_{5(s)}} SO_{3(g)}$$

Here, Catalyst is in Solid-phase while reactants are in gases phases. So, it is an example of heterogeneous catalysis.

C)  Catalytic hydrogenation is the addition of hydrogen to an unsaturated compound with a double or triple bond such as oil. The process of catalytic hydrogenation utilizes a metal catalyst such as nickel, palladium, or platinum. the reaction is shown as;

$$ Unsaturated_{(l)} +H_{2(g)} \xrightarrow{Ni_{(s)}} Saturated_{(l)}$$

Here, Catalyst is in Solid-phase while reactants are in gases phases. So, it is an example of heterogeneous catalysis.

D)  Acid hydrolysis of methyl acetate is catalyzed by dilute acid, where it gets converted to methanol and acetic acid. The reaction is shown as;
$$MeOCOCH_{3(aq.)} + H_2O_{(l)} \xrightarrow{H^+_{(aq)}} MeOH_{(aq.)} + AcOH_{(aq.)}$$

Here catalyst and the reactants both are in the liquid (Aqueous) phase so it is an example of Homogenous catalysis.

Final answer: Correct Option is $$D$$
Question 8
1 / -0

Detergents are less or non bio-degradable when compare with soaps. For detergents to be bio-degradable in nature, the non-polar part of the molecule should:

A
consist of a hydrocarbon with more branching

B
consist of a hydrocarbon with more number of branches and unsaturation

C
have straight or open chain hydrocarbons

D
be replaced by aromatic rings substituted by alkyl groups

Solution

Soaps are formed by the reaction of alkaline, fats, and oils. These are the sodium salts of fats and oils. Fats and oils can easily be broken down into simple molecules by microbes and hence soaps are biodegradable.
Detergents are synthetic compounds generally ammonium or sulfate salts of long chain carboxylic acids. These synthetic compounds cannot be broken down into simple molecules by microbes and hence detergents are non-biodegradable.
If detergents have a straight chain, then it could be easily be broken by molecules.
Question 9
1 / -0

Catalytic poisoning is due to:

A
increasing activation energy

B
adsorption of poisoner on the reactants surface

C
adsorption of poisoners on the catalyst surface

D
increase in heat of reaction

Solution

Catalyst poison, substance that reduces the effectiveness of a catalyst in a chemical reaction. They accumulate on the surface of solid catalysts and cause their effectiveness to decrease. For this reason, when the effectiveness of a catalyst has reached a certain low level, steps are taken to remove the poison or replenish the active catalyst component that may have reacted with the poison.
Question 10
1 / -0

In a reversible reaction, a catalyst :

A
increases the rate of the forward reaction only

B
increases the rate of forward reaction to a greater extent then that of the backward reaction

C
increases the rate of the forward reaction and decreases that of the backward reaction to different extent

D
increases the rate of the forward and backward reaction equally

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Surface Chemistry Test - 14

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Surface Chemistry Test - 14

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SHARING IS CARING

Question 1

dialysis

peptization

electrophoresis

electrosmosis

Solution

Question 2

Oxides of nitrogen

$$V_{2}O_{5}$$

$$Fe_{2}O_{3}$$

Platinised asbestos

Solution

Question 3

coagulation

vulcanization

peptization

flocculation

Solution

Question 4

catalyst

oxidising agent

reducing agent

dehydrating agent

Solution

Question 5

activation energy

dissociation energy

energy barrier

intermolecular forces

Solution

Question 6

Enzymes are in colloidal state

Enzymes are catalysts

Enzymes can catalyze any reaction

Urease is an enzyme

Solution

Question 7

Haber's process of synthesis of ammonia

Catalytic conversion of $$SO_{2}$$ to $$SO_{3}$$ in Contact process

Catalytic hydrogenation of oils

Acid hydrolysis of methyl acetate

Solution

Question 8

consist of a hydrocarbon with more branching

consist of a hydrocarbon with more number of branches and unsaturation

have straight or open chain hydrocarbons

be replaced by aromatic rings substituted by alkyl groups

Solution

Question 9

increasing activation energy

adsorption of poisoner on the reactants surface

adsorption of poisoners on the catalyst surface

increase in heat of reaction

Solution

Question 10

increases the rate of the forward reaction only

increases the rate of forward reaction to a greater extent then that of the backward reaction

increases the rate of the forward reaction and decreases that of the backward reaction to different extent

increases the rate of the forward and backward reaction equally

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