Surface Chemistry
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New answer posted
8 months agoContributor-Level 10
5.12
Extent of adsorption of a gas on a solid is influenced by following factors-
Nature of adsorbate
Nature of adsorbent
Pressure
Temperature
New answer posted
8 months agoContributor-Level 10
5.11
Finely divided substances have large surface area compared to not divided substance. And the increase in surface area increases the adsorption. Hence Finely divided substances are more effective adsorbent.
New answer posted
8 months agoContributor-Level 10
5.2
Physisorption | Chemisorption |
1) It happens due to Van there Waals forces. 2) It is reversible. 3) It is not specific in nature. 4) Low enthalpy of adsorption (20-40 KJ mol-1) 5) Low temperature is favourable. It decreases with increase in temperature. 6) Very less activation energy is needed. 7) It results in the multimolecular layer. | 1) It is caused by Chemical bond formation. 2) It is irreversible. 3) It is very specific in nature. 4) High enthalpy of adsorption (80-240 KJ mol-1) 5) The high temperature is favourable. It Increases with an increase in temperature. 6) High activation energy is needed. 7) It results in the unimolecular layer. |
New answer posted
8 months agoContributor-Level 10
5.9
Adsorption- The accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is termed as adsorption. In this substance accumulate at surface only and does not penetrate into the adsorbent (material on the surface of which adsorption takes place).
Ex- If gases like O2, H2, NH3 taken in a closed vessel containing charcoal then gases get adsorbed on the surface of charcoal and reduce the pressure.
Absorption- In this molecules get distributed uniformly throughout the material Instead of accumulating at the surface.
Ex- When gas like O2 is mixed with water then O2 get distributed throughout the solve
New answer posted
8 months agoContributor-Level 10
5.8
The precipitate which is obtained from a chemical reaction always contain some unwanted substances (eg ions, impurities) which get adsorbed onto the surface of the precipitate.
Therefore, it becomes important to wash the precipitate before estimating it quantitatively so as to remove these unwanted adsorbed substances and obtain accurate results.
New answer posted
8 months agoContributor-Level 10
5.7
According to Hardy-Schulze law
'The greater the valence of the flocculating ion added, the greater is its power to cause precipitation.
As this law takes into consideration of only the charge present on the ion and not the size of the ion. So when the size of the atom is considered, smaller the size of an atom more will be its polarising power.
So Hardy-Schulze can be modified in terms of the polarising power of the flocculating ion as 'The greater the polarising power of the flocculating ion added, the greater is its power to cause precipitation.
New answer posted
8 months agoContributor-Level 10
5.6
Desorption is a process in which substance (reactant + product) is released from the surface which is the opposite process of sorption.
The role of desorption in the process of catalysis is to make the surface of the solid catalyst-free for fresh adsorption of reactants on the solid surface for further reactions to take place.
New answer posted
8 months agoContributor-Level 10
5.5
Ester hydrolysis is represented as:
Ester + Water → Acid + Alcohol
In this reaction the acid produced which is a product also acts as a catalyst and makes the reaction faster.
Such substances that act as catalysts in the same reaction in which they are obtained as products are known as Autocatalysts.
So, ester hydrolysis is slow in the beginning and becomes faster after some time as more acid is produced on the product side.
New answer posted
8 months agoContributor-Level 10
5.4
It is important to remove CO (Carbon Monoxide) in the synthesis of ammonia as CO affects the activity of Iron catalyst which is required in Haber's process.
Note: Haber's process is a very important industrial process which is used to produce ammonia.
New answer posted
8 months agoContributor-Level 10
5.3
As Adsorption is directly proportional to the available surface area and powdered form of a substance have a greater surface area than the crystalline form of the substance.
So, greater the surface area of the adsorbent more is the adsorption.
Hence, powdered substances are more effective adsorbents than their crystalline forms
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