JEE Advanced Important Questions of Chemical Kinetics
FAQs on JEE Advanced Chemical Kinetics Important Questions
1. What is meant by the ‘rate’ of a chemical reaction according to JEE Advanced Chemical Kinetics Important Questions?
The rate of a chemical reaction, also known as the ‘reaction rate’ is the speed at which the reactants are converted to products. There are various reactions that take place almost instantaneously and also many other reactions that take a long, long time. Depending on the time taken by the reaction to fully convert all of its reactants to products, they can be classified as fast reactions, moderate reactions or slow (esterification) reactions. Alternatively, the rate of a reaction can also be defined as the rate of appearing of the products or the rate of disappearing of the reactants.
2. How do you determine the unit of the rate constant ‘k’?
As we have learned, the rate of a reaction is the speed with which the products appear or reactants disappear. This rate is directly proportional to the concentration of the reaction. Let’s take an example to fully understand this:
Consider the following chemical reaction:
aA + bB → cC + dD
Thus, Rate is directly proportional to (A)x(B)y
In order to remove the proportionality, we will introduce a constant of proportionality called the ‘Rate constant’ and denote it by k.
Rate = kAxBy
Where x and y are stoichiometric coefficients. The sum of x and y determine the order of the reaction.
Order = x + y
Depending on the order of the reaction, the units of k are as follows:
Order | Unit of k |
0 | mol L-1 s-1 |
1 | s1 |
2 | mol-1L s-1 |
3. In simple terms, how would you define the half life of a chemical reaction?
The time taken by the reaction to reduce the concentration of the reactants to half their initial value is known as the half life of the chemical reaction. It is denoted as t1/2. This value is used all round the medicine field in order to calculate the concentration of a given reactant at any given point of time. Depending on the order of the chemical reaction, the formula of half life of a reaction can be listed as:
Zero Order: t1/2 = 0.693/k
First Order: t1/2 =2.303tlog(2)0.693k
Where k is the rate constant. Students are expected to make note of these formulas since it is frequently asked in the exam. You can also check this article to know more about half life.
4. Mention some factors that affect the rate of the chemical reaction.
There are various factors that affect the rate of a chemical reaction, some influencing it whilst other making it slower. A few of them have been listed down below:
Physical state of the reactants: Gaseous reactants convert fastest to the product, followed by liquid and solid reactants.
Rate depending on state : Gaseous state> Liquid state>Solid state
Size of the reactants: The rate of the reaction is inversely proportional to the size of the reactants; larger the size, slower is the speed of conversion from reactants to products.
Concentration of the reactants: The rate of the reaction is directly proportional to the concentration, where more the concentration, faster the reaction takes place.
Read the textbook thoroughly to know more about other influencing factors such as temperature, chemical nature of the reactants, etc.
5. What are some important formulas mentioned in the JEE Advanced Chemical Kinetics Important Questions?
Chemical kinetics is loaded with tons of formulas that come in handy while solving the JEE paper. Not only is it helpful for this chapter, but also helps in the understanding of further chapters like Chemical equilibrium. Listing some important formulas down below:
Rate of reaction:
Rate of Reaction = \[\frac{Increase\: in\: Concentration\: of\: Product}{Time\: taken}\]=\[\frac{Decrease\: in\: Concentration\: of\: Reactant}{Time\: taken}\]
Unit of rate constant:
Order | Unit of k |
0 | mol L-1 s-1 |
1 | s1 |
2 | mol-1L s-1 |
Half life:
Zero Order: t1/2 = 0.693/k
First Order: t1/2 =2.303tlog(2)0.693k
Arrhenius Equation
\[K = Ae \frac{-Ea}{RT} \]
To know about each of the topics in detail, you can visit Chemical Kinetics - Definition, Formula, Equations and FAQs.
We hope you found this article useful and that you were able to solve the questions given in the document. What we seriously recommend the students to do is to carefully go through the solution given under each of the questions and try to check not only if your answer was correct but also if the method you used what's the most efficient one to get to the correct answer. How you manage your time is one of the key factors that determine whether you succeed in the JEE advanced and hence using the shortest path to get to the solution is just as important as getting to the right solution.
Students need to also make sure that if you could solve most of these questions on your own, you indeed are on the right path, but it is very important that you don't grow complacent. On the other hand if you struggled solving most of these questions, and constantly found yourself referring to the solution, it is nothing but a wakeup call that you need to relearn or revise this topic once again just to get a hold of it. In either case we are sure this article will help you prepare for the chemical kinetics topic which is very essential for the JEE advanced. Visit our official website for more such articles covering different subjects and topics that fall under the JEE syllabus.