Why are medicines more effective in colloidal state?

Medicines are more effective in colloidal state because colloids have a larger surface area. Thus, they get easily assimilated, absorbed and digested. Alternatively, a colloidal state has larger surface area of sol particles and this shows more effective adsorption. Thus, medicines in colloidal state are more effectively absorbed and give better results.

Give three points of difference between physisorption and chemisorption.

Physisorption Chemisorption Physisorption is caused by the van der waals forces between adsorbate and adsorbent Chemisorption is caused by the formation of chemical bond between two molecules It is not specific in nature. It is highly specific in nature It is a reversible process. It is irreversible process.

What happens when an emulsion is centrifuged?

When an emulsion is centrifuged, demulsification takes place, i.e. the emulsion is broken into constituent liquids. The lighter water stays towards the centre of the centrifuge and the heavier oil stays on the outside.

What happens when persistent dialysis of a colloidal solution is carried out?

The stability of colloidal solution is due to the presence of a small amount of electrolyte. On persistent dialysis, the electrolyte present is completely removed. As a result, the colloidal solution becomes unstable and gets coagulated.

What happens when a freshly prepared precipitate of Fe ( OH ) 3 is shaken with a small amount of FeCl 3 solution?

When a freshly prepared precipitate of Fe ( OH ) 3 is shaken with a small amount of FeCl 3 solution, a reddish-brown colloidal solution of Fe ( OH ) 3 is obtained. This process is called peptization. The Fe 3 + ions from FeCl 3 are adsorbed on the surface of the precipitate to form a positively charged colloidal solution. FeCl 3 → Fe 3 + + 3 Cl - Fe OH 3 + Fe 3 + → Fe OH 3 Fe 3 + Colloidal solution

How does chemisorption vary with temperature?

Chemisorption increases with temperature up to a certain extent as then after it starts decreasing. Chemisorption occurs due to a chemical reaction between adsorbate and adsorbent, and chemical reactions increase with the increase in temperature.

A colloidal sol is prepared by the given method in the figure. What is the charge on hydrated ferric oxide colloidal particles formed in the test tube? How is the sol represented?

In the given method, FeCl 3 is being added to the sodium hydroxide solution to give a sol of hydrated ferric oxide, Fe 2 O 3 . xH 2 O . The sol formed preferentially adsorbs the negatively charged hydroxide ions present in the solution and hence acquire a negative charge on sol particles. The negatively charged sol formed can be represented as Fe 2 O 3 . xH 2 O / OH – .

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter -1 - Surface Chemistry>CBSE-2019>Q 6

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