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

Why can’t molecularity of any reaction be equal to zero? - Chemistry

Advertisements
Advertisements

प्रश्न

Why can’t molecularity of any reaction be equal to zero?

टीपा लिहा
Advertisements

उत्तर

The number of molecules of the reactants involved in an elementary reaction is referred to as the molecularity of the reaction. For this, a single molecule with a minimum molecularity of one is required, and it cannot be zero.

shaalaa.com
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 4: Chemical Kinetics - Exercises [पृष्ठ ५६]

APPEARS IN

एनसीईआरटी एक्झांप्लर Chemistry [English] Class 12
पाठ 4 Chemical Kinetics
Exercises | Q III. 50. | पृष्ठ ५६

संबंधित प्रश्‍न

A → B is a first order reaction with rate 6.6 × 10-5m-s-1. When [A] is 0.6m, rate constant of the reaction is

  • 1.1 × 10-5s-1
  • 1.1 × 10-4s-1
  • 9 × 10-5s-1
  • 9 × 10-4s-1

For a reaction: 

Rate = k

(i) Write the order and molecularity of this reaction.

(ii) Write the unit of k.


For the hydrolysis of methyl acetate in aqueous solution, the following results were obtained :

t/s 0 30 60
[CH3COOCH3] / mol L–1 0.60 0.30 0.15

(i) Show that it follows pseudo first order reaction, as the concentration of water remains constant.

(ii) Calculate the average rate of reaction between the time interval 30 to 60 seconds.

(Given log 2 = 0.3010, log 4 = 0.6021)


For a reaction, \[\ce{A + B -> Product}\]; the rate law is given by, `r = k[A]^(1/2)[B]^2`. What is the order of the reaction?


From the rate expression for the following reaction, determine the order of reaction and the dimension of the rate constant.

\[\ce{CH3CHO_{(g)} -> CH4_{(g)} + CO_{(g)}}\] Rate = k [CH3CHO]3/2


For the reaction:

\[\ce{2A + B → A2B}\] 

the rate = k[A][B]2 with k = 2.0 × 10−6 mol−2 L2 s−1. Calculate the initial rate of the reaction when [A] = 0.1 mol L−1, [B] = 0.2 mol L−1. Calculate the rate of reaction after [A] is reduced to 0.06 mol L−1.


A reaction is first order in A and second order in B. How is the rate affected on increasing the concentration of B three times?

 


Which of the following statement is true for order of a reaction?


Consider a first order gas phase decomposition reaction given below :
\[\ce{A(g) -> B(g) + C(g)}\]
The initial pressure of the system before decomposition of A was pi. After lapse of time ‘t’, total pressure of the system increased by x units and became ‘pt’ The rate constant k for the reaction is given as ______.


Rate law for the reaction \[\ce{A + 2B -> C}\] is found to be Rate = k [A][B]. Concentration of reactant ‘B’ is doubled, keeping the concentration of ‘A’ constant, the value of rate constant will be ______.


For a complex reaction:

(i) order of overall reaction is same as molecularity of the slowest step.

(ii) order of overall reaction is less than the molecularity of the slowest step.

(iii) order of overall reaction is greater than molecularity of the slowest step.

(iv) molecularity of the slowest step is never zero or non interger.


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?


Assertion: Rate constants determined from Arrhenius equation are fairly accurate for simple as well as complex molecules.

Reason: Reactant molecules undergo chemical change irrespective of their orientation during collision.


A catalyst in a reaction changes which of the following?


The rate constant for the reaction \[\ce{2H2O5 -> 4NO2 + O2}\] is 30 × 10–5 sec–1. if the rate is 204 × 10–5 mol L1 S1, then the concentration of N2O5 (in mol1) is-


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?


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]

On heating compound (A) gives a gas (B) which is constituent of air. The gas when treated with H2 in the presence of catalyst gives another gas (C) which is basic in nature, (A) should not be ______.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×