Chemisorption

Q.

The correct statement(s) pertaining to the adsorption of a gas on a solid surface is (are)

1. Adsorption is always exothermic.

2. Physisorption may transformation into chemisorption at high temperature.

3. Physisorption increases with increasing temperature but chemisorption decreases with increasing temperature.

4. Chemisorption is more exothermic than physisorption; however, it is very slow due to higher energy of activation.

Q.

How many layers are adsorbed in chemical adsorption?

1. One
2. Two
3. Many
4. Zero

Q.

The rate of chemisorption :

1. increases with increase of pressure
2. is independent of pressure
3. is independent of temperature
4. decreases with increase of pressure

Q. The given graph/data I, II, III and IV represent general trends observed for different physisorption and chemisorption processes under mild conditions of temperature and pressure. Which of the following choice(s) about I, II, III and IV is (are) correct?

1. I is physisorption and II is chemisorption
2. I is physisorption and III is chemisorption
3. IV is chemisorption and II is chemisorption
4. IV is chemisorption and III is chemisorption

Q.

Chemisorption

1. Remains unaffected by change of temperature

2. Either increases or decreases with temperature

3. Increases with temperature

4. Decreases with temperature

Q.

Chemisorption

1. Decreases with increase of temperature

2. Involves multilayer formation of adsorbent on adsorbate

3. Is irreversible in nature

4. Involves the weak attractive interactions between adsorbent and adsorbate

Q.

1 g charcoal adsorbs 100 ml of 0.5 M $C{H}_{3}CHOOH$ to form a monolayer. As a result molarity of acetic acid reduces to 0.49 M. What will be the surface area covered by each molecule of acetic acid? Given that surface area of charcoal $=3.01\times {10}^2{m}^2/g$.

1. 2.5 × 10^-19 m²
2. 5.0 × 10^-19 m²
3. 10^–18 m²
4. 2.0 × 10^-18 m²

Q.

Enthalpy of chemisorption is in the order of?

1. 20 - 40 kJ per mol

2. 80 - 240 kJ per mol

3. 30 - 1000 kJ per mol

4. 40 - 80 kJ per mol

Q. Which of the following is correct for chemical adsorption?

1. Increases with an increase in temperature
2. Decreases with an increase in temperature
3. First increases, then decreases with an increase in temperature
4. First decreases, then increases with an increase in temperature

Q. When dioxygen is adsorbed on a metallic surface, the electron transfer occurs from the metal to the molecule. The true statements regarding this adsorption are:

1. $O_2$ is physisorbed
2. Heat is released
3. Occupancy of ${\pi }_{2px}^{\ast }$ $O_2$ is increased
4. Bond length of $O_2$ is increased