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In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion : The enthalpy of reaction remains constant in the presence of a catalyst.
Reason : A catalyst participating in the reaction, forms a different activated complex and lowers down the activation energy but the difference in energy of reactant and product remains the same.
  • a)
    Both assertion and reason are true and the reason is the correct explanation of assertion.
  • b)
    Both assertion and reason are true but the reason is not the correct explanation of assertion.
  • c)
    Assertion is true but reason is false.
  • d)
    Assertion is false but reason is true.
Correct answer is option 'A'. Can you explain this answer?
Verified Answer
In the following questions a statement of assertion followed by a sta...
It is believed that the catalyst provides an alternate pathway or reaction mechanism by reducing the activation energy between reactants and products and hence lowering the potential energy barrier but the enthalpy of reaction remains constant.
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Most Upvoted Answer
In the following questions a statement of assertion followed by a sta...
Assertion: The enthalpy of reaction remains constant in the presence of a catalyst.
Reason: A catalyst participating in the reaction forms a different activated complex and lowers down the activation energy, but the difference in energy of reactant and product remains the same.

Explanation:
A catalyst is a substance that increases the rate of a chemical reaction by providing an alternative reaction pathway with a lower activation energy. It does not undergo any permanent change in its own composition during the reaction.

The given assertion states that the enthalpy of the reaction remains constant in the presence of a catalyst. Enthalpy is a measure of the heat energy change during a chemical reaction. According to the reason provided, a catalyst forms a different activated complex and lowers down the activation energy.

Let's analyze the given options:

a) Both assertion and reason are true and the reason is the correct explanation of the assertion.
b) Both assertion and reason are true but the reason is not the correct explanation of the assertion.
c) Assertion is true but reason is false.
d) Assertion is false but reason is true.

To determine the correct answer, let's examine the explanation further.

1. The Role of a Catalyst:
- A catalyst provides an alternative reaction pathway with a lower activation energy.
- It does not affect the energy difference between the reactants and products.
- A catalyst lowers the activation energy barrier but does not change the overall energy change of the reaction.
- It speeds up the rate of the reaction by making it easier for the reactants to reach the activated complex and form the products.

2. Enthalpy of Reaction:
- The enthalpy of reaction is the difference in energy between the reactants and products.
- It represents the heat energy change during a chemical reaction.
- The enthalpy change remains the same whether a reaction occurs with or without a catalyst.

Therefore, the correct answer is option 'A' - Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

In conclusion, the presence of a catalyst does not affect the enthalpy of reaction because it only provides an alternative reaction pathway with a lower activation energy. The catalyst does not change the overall energy change of the reaction, and thus, the enthalpy remains constant.
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Read the passage given below and answer the following questions:Nucleophilic substitution reaction of haloalkane can be conducted according to both SN1 and SN2 mechanisms. However, which mechanism it is based on is related to such factors as the structure of haloalkane, and properties of leaving group, nucleophilic reagent and solvent. Influences of halogen: No matter which mechanism the nucleophilic substitution reaction is based on, the leaving group always leave the central carbon atom with electron pair. This is just the opposite of the situation that nucleophilic reagent attacks the central carbon atom with electron pair. Therefore, the weaker the alkalinity of leaving group is , the more stable the anion formed is and it will be more easier for the leaving group to leave the central carbon atom; that is to say, the reactant is more easier to be substituted. The alkalinity order of halogen ion is I− < Br− < Cl− < F− and the order of their leaving tendency should be I− > Br− > Cl− > F−. Therefore, in four halides with the same alkyl and different halogens, the order of substitution reaction rate is RI > RBr > RCl > RF. In addition, if the leaving group is very easy to leave, many carbocation intermediates are generated in the reaction and the reaction is based on SN1 mechanism. If the leaving group is not easy to leave, the reaction is based on SN2 mechanism. Influences of solvent polarity: In SN1 reaction, the polarity of the system increases from the reactant to the transition state, because polar solvent has a greater stabilizing effect on the transition state than the reactant, thereby reduce activation energy and accelerate the reaction. In SN2 reaction, the polarity of the system generally does not change from the reactant to the transition state and only charge dispersion occurs. At this time, polar solvent has a great stabilizing effect on Nu than the transition state, thereby increasing activation energy and slow down the reaction rate. For example, the decomposition rate (SN1) of tertiary chlorobutane in 25° water (dielectric constant 79) is 300000 times faster than in ethanol (dielectric constant 24). The reaction rate (SN2) of 2-bromopropane and NaOH in ethanol containing 40% water is twice slower than in absolute ethanol. In a word, the level of solvent polarity has influence on both SN1 and SN2 reactions, but with different results. Generally speaking, weak polar solvent is favorable for SN2 reaction, while strong polar solvent is favorable for SN1 reaction, because only under the action of polar solvent can halogenated hydrocarbon dissociate into carbocation and halogen ion and solvents with a strong polarity is favorable for solvation of carbocation, increasing its stability. Generally speaking, the substitution reaction of tertiary haloalkane is based on SN1 mechanism in solvents with a strong polarity (for example, ethanol containing water).Q. Polar solvents make the reaction faster as they

In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.Assertion : The enthalpy of reaction remains constant in the presence of a catalyst.Reason : A catalyst participating in the reaction, forms a different activated complex and lowers down the activation energy but the difference in energy of reactant and product remains the same.a)Both assertion and reason are true and the reason is the correct explanation of assertion.b)Both assertion and reason are true but the reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Assertion is false but reason is true.Correct answer is option 'A'. Can you explain this answer?
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In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.Assertion : The enthalpy of reaction remains constant in the presence of a catalyst.Reason : A catalyst participating in the reaction, forms a different activated complex and lowers down the activation energy but the difference in energy of reactant and product remains the same.a)Both assertion and reason are true and the reason is the correct explanation of assertion.b)Both assertion and reason are true but the reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Assertion is false but reason is true.Correct answer is option 'A'. Can you explain this answer? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.Assertion : The enthalpy of reaction remains constant in the presence of a catalyst.Reason : A catalyst participating in the reaction, forms a different activated complex and lowers down the activation energy but the difference in energy of reactant and product remains the same.a)Both assertion and reason are true and the reason is the correct explanation of assertion.b)Both assertion and reason are true but the reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Assertion is false but reason is true.Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.Assertion : The enthalpy of reaction remains constant in the presence of a catalyst.Reason : A catalyst participating in the reaction, forms a different activated complex and lowers down the activation energy but the difference in energy of reactant and product remains the same.a)Both assertion and reason are true and the reason is the correct explanation of assertion.b)Both assertion and reason are true but the reason is not the correct explanation of assertion.c)Assertion is true but reason is false.d)Assertion is false but reason is true.Correct answer is option 'A'. Can you explain this answer?.
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