Tag: adsorption and colloids
Questions Related to adsorption and colloids
The process which is catalysed by one of the products is called:
-
acid-base catalysis
-
autocatalysis
-
negative catalysis
-
positive catalysis
The process which is catalyzed by one of the products is called is called auto-catalysis.The product used for the catalysis is auto catalyst.
In case of autocatalysis:
-
reactant catalyses
-
heat produced in the reaction catalyses
-
product catalyses
-
solvent catalyses
Autocatalysis is the reaction where one of the products formed catalyzes the reaction. So in case of auto catalysis product catalyses the reaction. Hence catalysis of a reaction by one of its products is called autocatalysis.
Which of the following are correct about the catalyst?
-
They participate in the reaction but recovered at last
-
It does not affect $\Delta G $
-
It increases $\Delta G $
-
It alters the mechanism of reaction
The catalyst is the substance which increases the rate of reaction by lowering the activation energy which alters the mechanism of the reaction.
Which statement of the following is false for a catalyst?
-
A catalyst can initiate a reaction.
-
It does not alter the position of equilibrium in a reversible reaction.
-
A catalyst remains unchanged in quality and composition at the end of the reaction.
-
Catalysts are sometimes very specific in reaction.
Catalysis is the increase in the rate of a chemical reaction due to the participation of an additional substance called a catalyst which is not consumed in the catalysed reaction and can continue to act repeatedly.It increase rate of forward as well as backward reaction.
In presence of a catalyst, the activation energy is lowered by 3 kcal at $27^o C$. Hence, the rate of reaction will increase by:
-
32 times
-
243 times
-
3 times
-
48 times
$K={Ae}^{\dfrac{-Ea}{RT}}$
Which of the following statements is correct about solid catalysts?
-
Catalyst is required in equal amount as the reactants present in the reaction.
-
Catalytic activity of a solid catalyst does not depend upon the extent of chemisorption.
-
Desorption is not important for a solid to act as good catalyst.
-
Same reactants may give different products by using different catalysts.
- For a given chemical reaction the amount of catalyst used is not necessarily to be equal to that of reactants.
- Catalytic activity of a solid catalyst depends upon the extent of chemisorption because of the various bonds formed.
- A catalyst is called a good catalyst if not only catalyses the reaction but also gives space for further reaction over its surface .i.e Desorption is a important characteristic.
- It is not necessary that a reaction to give same products if we use different catalysts, for different cataysts the products may be different.
An inhibitor is described as:
-
a substance that slows down or stops a reaction
-
a substance which inhibits the properties of a catalyst
-
a substance formed during the reaction and does not participate in the reaction
-
a substance which prevents formation of products in a reaction being most reactive
A reaction inhibitor is a substance that decreases the rate of, or prevents, a chemical reaction. A catalyst, in contrast, is a substance that increases the rate of a chemical reaction.
Presence of traces of arsenious oxide ($As _{2}O _{3}$) in the reacting gases $SO _{2}$ and $O _{2}$ in presence of platinised asbestos in contact process acts as:
-
catalytic promoter
-
catalytic poison
-
dehydrating agent
-
drying agent.
- Promoters are substances that enhance the activity of a catalyst while poisons decrease the activity of a catalyst.
- In the manufacturing of sulfuric acid, a step involves the reaction of $SO _2$ and $O _2$ in presence of platinized asbestos to give $SO _3$
Which are not examples of autocatalysis?
-
Breakdown of atomic fuel in reactor.
-
Shock decomposition of glycerol trinitrate.
-
ZSM-5 used to convert alcohol in petrol.
-
Storage of chloroform along with little ethanol.
A chemical reaction is said to have undergone autocatalysis if the reaction product itself is the catalyst for that reaction.
Shock decomposition of glycerol trinitrate is autocatalysis due to the mixture of gases which acts as autocatalyst. The reaction is as follows:
$4C _3 H _5 (ONO _2) _3 \rightarrow 12CO _2 + 10H _2O + 6N _2 +O _2$
Select the correct statement(s).
-
Enzyme catalysed reactions are highly specific
-
Enzyme catalysed reactions are highly susceptible to $pH$ and temperature
-
Decomposition of glyceryl trinitrate is an example of autocatalysis
-
The acid hydrolysis and alkaline hydrolysis of ester are reversible