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कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान 2nd PUC Class 12

Why does the rate of any reaction generally decreases during the course of the reaction?

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प्रश्न

Why does the rate of any reaction generally decreases during the course of the reaction?

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उत्तर

The rate of a reaction depends on the concentration of reactants. As the reaction progresses, the concentration of reactants decreases because the reactants start getting converted to products. Hence the rate decreases.

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अध्याय 4: Chemical Kinetics - Exercises [पृष्ठ ५६]

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एनसीईआरटी एक्झांप्लर Chemistry Exemplar [English] Class 12
अध्याय 4 Chemical Kinetics
Exercises | Q III. 47. | पृष्ठ ५६

संबंधित प्रश्न

Define “zero order reaction”.


For a reaction A + B ⟶ P, the rate is given by

Rate = k [A] [B]2

What is the overall order of reaction if A is present in large excess?


The conversion of molecules X to Y follows second order kinetics. If concentration of X is increased to three times how will it affect the rate of formation of Y?


Mention the factors that affect the rate of a chemical reaction.


In a reaction between A and B, the initial rate of reaction (r0) was measured for different initial concentrations of A and B as given below:

A/mol L−1 0.20 0.20 0.40
B/mol L−1 0.30 0.10 0.05
r0/mol L−1 s−1 5.07 × 10−5 5.07 × 10−5 1.43 × 10−4

What is the order of the reaction with respect to A and B?


Write the principle behind the following methods of refining:

Hydraulic washing


Rate of reaction for the combustion of propane is equal to:

\[\ce{C3H8_{(g)} + 5O2_{(g)} -> 3CO2_{(g)} + 4H2O_{(g)}}\]


Molecularity of a reaction _____________.


The value of rate constant of a pseudo first order reaction ______.


In any unimolecular reaction:

(i) only one reacting species is involved in the rate determining step.

(ii) the order and the molecularity of slowest step are equal to one.

(iii) the molecularity of the reaction is one and order is zero.

(iv) both molecularity and order of the reaction are one.


In a reaction if the concentration of reactant A is tripled, the rate of reaction becomes twenty seven times. What is the order of the reaction?


Use Molecular Orbital theory to determine the bond order in each of species, [He2j+ and [He2]2+?


The role of a catalyst is to change


In the presence of a catalyst, the heat evolved or absorbed during the reaction.


For the reaction, \[\ce{A +2B → AB2}\], the order w.r.t. reactant A is 2 and w.r.t. reactant B. What will be change in rate of reaction if the concentration of A is doubled and B is halved?


Identify the order of reaction from the following unit for its rate constant:

L mol–1 s–1


Read the following passage and answer the questions that follow:

The rate of reaction is concerned with decrease in the concentration of reactants or increase in the concentration of products per unit of time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law:

Rate = k[A]x [B]y

x and y indicate how sensitive the rate is to change in concentration of A and B. Sum of x + y gives the overall order of a reaction.
When a sequence of elementary reactions gives us the products, the reaction is called complex reaction. Molecularity and order of an elementary reaction are same. Zero-order reactions are relatively uncommon but they occur under special conditions. All natural and artificial radioactive decay of unstable nuclei takes place by first-order kinetics.

  1. What is the effect of temperature on the rate constant of a reason?    [1]
  2. For a reaction \[\ce{A + B → Product}\], the rate law is given by, Rate = k[A]2 [B]1/2. What is the order of the reaction?    [1]
  3. How order and molecularity are different for complex reactions?    [1]
  4. A first-order reaction has a rate constant 2 × 10–3 s–1. How long will 6 g of this reactant take to reduce to 2 g?    [2]
    OR
    The half-life for radioactive decay of 14C is 6930 years. An archaeological artifact containing wood had only 75% of the 14C found in a living tree. Find the age of the sample.
    [log 4 = 0.6021, log 3 = 0.4771, log 2 = 0.3010, log 10 = 1]    [2]

A drop of solution (volume 0.05 ml) contains 3.0 × 10-6 mole of H+. If the rate constant of disappearance of H+ is 1.0 × 107 mole l-1s-1. It would take for H+ in drop to disappear in ______ × 10-9s.


Assertion (A): Order of reaction is applicable to elementary as well as complex reactions.

Reason (R): For a complex reaction, molecularity has no meaning.


Which of the following statement is true?


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