Tag: adsorption and colloids
Questions Related to adsorption and colloids
The minimum energy level necessary to permit a reaction to occur is:
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internal energy
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threshold energy
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activation energy
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free energy
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.
Which of the following is/are not possible in case of auto-catalysis?
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Reactant catalysis.
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Heat produced in the reaction catalysis.
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Product catalysis.
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Solvent catalysis.
Chemical equilibrium is ____ by a catalyst.
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not affected
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affected
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some time affected
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none of the above
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 ______ of the reaction acts as a catalyst.
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intermediates
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products
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reactants
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none of the above
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.
$\displaystyle 2KMnO _4 + 3H _2SO _4 +5H _2C _2O _4 \rightarrow K _2O _4 +2MnSO _4 +8H _2O +10CO _2$
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True
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False
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True
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False
The given statement is true.
Activation energy is always lowered by positive catalyst. This increases the rate of the reaction.
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True
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False
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 which condition is not essential :
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Variable valency
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High ionisation energy
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Empty orbitals
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Free valency on the surface
For a catalyst, high ionization energy is not essential.
The essential conditions include variable valency, empty orbitals and free valency on the surface.
The catalyst is a substance which:
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increases the yield of the reaction
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increases the speed of the reaction
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decreases the speed of the reaction
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increases the speed of the reaction and remains unchanged.
Catalyst is a substance that changes (usually increases) the rate of a reaction, without being involved in the reaction. A catalyst provides large surface area to one of the reactants, providing it an exposure to be reacted upon by the other reactant.
During hydrogenation reaction, H-H bond splits and hydrogen atoms are attached to Ni catalyst through through strong chemical forces.
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True
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False
In hydrogenation reaction, the H-H bond splits and the hydrogen atom is chemically bonded to the Ni catalyst.