(i) What is the role of activated charcoal in gas mask?
(ii) A colloidal sol is prepared by the given method in figure. What is the charge on hydrated ferric oxide colloidal particles formed in the test tube? How is the sol represented?
(iii) How does chemisorption vary with temperature?
Ans for option (i)
Activated charcoal or activated carbon is a solid with high surface area and greater micro porosity which gives 3,000 m2 surface area for just one gram of activated carbon!
This large surface area helps in adsorption of harmful and unnecessary particulate matter and chemicals in the atmosphere. Thus activated charcoal is used in gas mask to prevnet smoke and chemicals to enter the respiratory system.
Option (ii)
FeCl3 is a salt but with weak hydration energy. When it comes with NaOH it can form a stronger Na+Cl- ionic bond that has higher heat of hydration and is more stable. Due to this OH- ions are adsorped and a negatively charged sol is obtained.
Sol will be represented as follows:
Option (iii)
Chemisorption is the adsorption of chemical species by undergoing chemical bonding with the reactant. The reactant and undergoes chemical changes during a chemisorption process. Depending on the type of reaction and the nature of surface it varies with temperature for different substances.
As the temperature is increased the molecules that need to cross the activation energy barrier is reached faster and the rate of chemisorption increases with temperature. After a certain raise in temperature, further increase will superheat the molecules or give them enough momentum so that they do not come in contact to react leading to decrease in the rate of adsorption.
