Intext Questions Chemical Kinetics

Unit-4 Chemical Kinetics
In-Text Questions

4.1. For the reaction R ® P, the concentration of a reactant changes from 0.03M to 0.02M in 25 minutes. Calculate the average rate of reaction using units of time both in minutes and seconds.











4.2. In a reaction, 2A ® Products, the concentration of A decreases from 0.5 mol L-1 to 0.4 mol L-1 in 10 minutes. Calculate the rate during this interval?








 4.3. For a reaction, A + B ® Product; the rate law is given by, r = k [ A]1/2 [B]2. What is the order of the reaction?

 

Ans: The sum of powers of the concentration of the reactants in the rate law expression is called the order of that chemical reaction.

Therefore,

 

Order = ½ + 2 = 5 / 2 = 2.5

 

 

4.4. 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 ?

 

Ans: Rate = k [A]2

 

When concentration of [A] is increased 3 times, then

 

Rate’ = k [3A]2 = 9 k [A]2

 

Rate’ = 9 x Rate.

 

Therefore, Rate of formation of Y will be 9 times.

 

 

4.5. A first order reaction has a rate constant 1.15 × 10-3 s-1. How long will 5 g of this reactant take to reduce to 3 g?
















4.6. Time required to decompose SO2Cl2 to half of its initial amount is 60 minutes. If the decomposition is a first order reaction, calculate the rate constant of the reaction.











4.7. What will be the effect of temperature on rate constant ?

 Ans: The rate constant of a reaction increases with increase in temperature.

  

4.8. The rate of the chemical reaction doubles for an increase of 10K in absolute

temperature from 298K. Calculate Ea.















4.9. The activation energy for the reaction 2 HI(g) ® H2 + I2 (g) is 209.5 kJ mol-1 at 581K. Calculate the fraction of molecules of reactants having energy equal to or greater than activation energy?


      







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