Tag: catalysis

In a reversible reaction, a catalyst increases the rate of the forward and backward reactions equally.
An increase in rate of reaction in forward direction by a catalyst for a reaction in equilibrium brings in an increase in concentration of products at faster rate and thus, rate of backward reaction also increases to same magnitude and the equilibrium position is not altered. In such reactions equilibrium constant does not alters.

Option (B) is correct.
Catalyst does not alter the state of equilibrium. In the presence of a catalyst, both the forward and reverse reaction rates will speed up equally, thereby allowing the system to reach equilibrium faster. The addition of a catalyst has no effect on the final equilibrium position of the reaction.

The minimum energy level necessary to permit a reaction to occur is called threshold energy.
Threshold energy is the energy level where some chemical/physical action happens. Threshold energy for production of a particle is the minimum kinetic energy a pair of traveling particles must have when they collide. The threshold energy is always greater than or equal to the rest energy of the desired particle.

A set of chemical reactions can be said to be collectively autocatalytic if a number of those reactions produce, as reaction products, catalysts for enough of the other reactions that the entire set of chemical reactions is self-sustaining given an input of energy and food molecules.

Chemical equilibrium is not affected by a catalyst.
When a catalyst is used, the equilibrium is achieved faster but the value of the equilibrium constant remains unaffected.

In auto-catalysis, one of the products of the reaction acts as a catalyst.
For example, when oxalic acid is titrated with $\displaystyle KMnO _4 $ in presence of dil $\displaystyle H _2SO _4 $, the colour of $\displaystyle KMnO _4 $ first fades slowly and then faster due to the formation of $\displaystyle Mn^{2+} $ ions which act as auto catalyst.
$\displaystyle 2KMnO _4 + 3H _2SO _4 +5H _2C _2O _4 \rightarrow K _2O _4 +2MnSO _4 +8H _2O +10CO _2$

Enzyme activators are molecules that bind to enzymes and increase their activity. They are the opposite of enzyme inhibitors. These molecules are often involved in the allosteric regulation of enzymes in the control of metabolism.

The given statement is true.
Activation energy is always lowered by positive catalyst. This increases the rate of the reaction.

The given statement is true.
A catalyst remains unchanged chemically at the end of the reaction. It may take part in the reaction mechanism. It may be consumed in the first step and regenerated in the second step.

For a catalyst, high ionization energy is not essential.
The essential conditions include variable valency, empty orbitals and free valency on the surface.