Chemistry Class 12 NCERT Solutions: Chapter 4 Chemical-Kinetic Part 1

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Q: 1. For the reaction , the concentration of a reactant changes from minutes. Calculate the average rate of reaction using units of time both in minutes and seconds.


Average rate of reaction

Q: 2. In a reaction, Products, the concentration of A decreases from minutes. Calculate the rate during this interval?


Q: 3. For a reaction, Product; the rate law is given by, . What is the order of the reaction?


The order of the reaction

Q: 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?


The order of reaction is defined as the sum of the powers of concentrations In the rate law.

The rate of second order reaction can be expressed as

The reaction follows second order kinetics.

Therefore, the rate equation for this reaction will be:


Let , then equation (1) can be written as:

If the concentration of X is increased to three times, then

Now, the rate equation will be:

Hence, the rate of formation will increase by times.

Q: 5. A first order reaction has a rate constant . How long will g of this reactant take to reduce to ?


From the question, we can write down the following information:

Initial amount

Final concentration

Rate constant

We know that for a 1st order reaction,