The precipitate is formed from reactions so it contains some chemical or unwanted substances traces (like impurities, catalyst and reactant). For quantitative estimation of the product, we need to remove these additional substances which get adsorbed onto the surface of the required product and it gives us the wrong information about the product of the reaction. So to avoid this problem we wash...
According to Hardy-Schulze law that ‘the higher the valence of the flocculating ion added, the higher is its power to cause precipitation. Here he does not about the size of the ion, which polarises the other oppositely charged ion. Hence the modified law should be "the greater the polarising power of flocculating ion added, the greater is its power to cause precipitation."
In catalytic reaction, the reactant attached on the surface of the catalyst and form complex and after some procedure, it becomes the product of the reaction. We need to detach it from the surface of the catalyst to get the product and catalyst separately and hereby desorption process, we can get the product.
Initially, the reaction is slow but after some time the reaction is fast because of the acid produced, act as a catalyst for this reaction. These type of reaction known as auto-catalysis.
Since adsorption is a surface phenomenon. So, the extent of adsorption directly depends on the surface area. Thus, the powdered substances more effective absorbents than their crystalline forms due to their large surface area which can adsorb more gas as compared to the crystalline form.
Two characteristics of Chemisorption-
The bond formation between the solid(adsorbent) and the gas molecules is by chemical bonds like a covalent bond or ionic bond.
It is highly specific in nature and also irreversible.