Get plus subscription and access unlimited live and recorded courses

The chapter kinetic theory of gases starts with the basic revision of all the concepts we studied in our lower grades to build the connection between the advanced parts of the kinetic theory of gases. In the kinetic theory of gases we have discussed the molecular nature of matter, behaviour of gases, kinetic theory of an ideal gas, law of equipartition of energy, specific heat capacity, mean free path etc.

The chapter Kinetic theory of gases deals with macroscopic to microscopic properties of gas which includes quantities like temperature, pressure,speed and kinetic energy.

Moving further we got introduced to a few more important concepts like the law of equipartition of energy,degrees of freedom and Maxwell’s distribution of molecular speeds.

Now, let us move on to the important concepts and formulae related to NEET and NEET mains exams along with a few solved examples.

Behaviour of Gas Molecules

Ideal Gas Equation

Kinetic Theory of an Ideal Gas

Kinetic Interpretation of temperature

Degree of Freedom

Law of Equipartition of Energy

Calculate the rms speed of nitrogen at STP(pressure =1atm and temperature = $0^{\circ}$ C. The density of nitrogen in these conditions is 1.25kg/m3.

Sol:

Given,

At STP the pressure is $1 \times 10^{5}$ N/m2

hence the rms speed is $v_{rms} = 1.73\sqrt{\dfrac{p}{⍴} }$

where p is the pressure of gas and ⍴ is the density

So $v_{rms}$ = $1.73\sqrt{\dfrac{10^{5}}{1.25}}}$ = 490m/s

Key point: Here only the formula of $v_{rms}$ should be remembered by the student.

Calculate the number of molecules in each cubic metre of a gas at 1atm and $27^{\circ}$ C.

Sol:

From the ideal gas equation PV=nRT

Where P is the pressure of gas

R= gas constant

V = volume of gas

T= temperature of gas and n = no. of molecules

Hence n = $\dfrac{PV}{RT}$

=$\dfrac{10^{5}}{300\times 1.38\times 10^{-23 }}$

Hence n = $2.4\times 10^{5}$

Key point: Here only the formula of ideal gas equation should be remembered by the student

Previous Year Questions

A gas mixture consists of 2 moles of $O_{2}$ and 4 moles of Ar at temperature T. Neglecting all the vibrational modes, the total internal energy of the system is:- (NEET 2017)

Sol:

Here oxygen being a diatomic molecule will have no vibrational mode

So U(oxygen) = $2\times\dfrac{5}{2}RT$= 5RT

Similarly argon being monoatomic gas having only translational mode has 4 moles

So U(Ar) = $4\times\dfrac{3}{2}RT$ = 6RT

Hence total internal energy of system = U(oxygen)+ U(Ar) = 11RT

Trick: Here only the concept of degrees of freedom should be remembered by the student with the formula $U = \dfrac{U}{2RT}$

A given sample of an ideal gas occupies a volume V at a pressure P and absolute temperature T. The mass of each molecule of the gas is m. Which of the following gives the density of the gas? (NEET 2016)

Sol:

From ideal gas equation

PV= nRT

And n = $\dfrac{PV}{RT}$

Also we know that k = $\dfrac{R}{N_{a}}$

$\dfrac{nN_{a}}{V}$ = $\dfrac{P}{kT}$

Multiplying both sides with m and after calculations we have

Density = $\dfrac{mP}{kT}$

Trick: Here only the formula of the ideal gas equation should be remembered by the student.

The translational kinetic energy of molecules of one mole of monatomic gas is U=$\dfrac{3NKT}{2}$. The value of atomic specific heat of gas under constant pressure will be: (Ans:- $\dfrac{5}{2}R$)

A gas is at zero degree celsius. Upto what temp the gas has to be heated so that the root mean square velocity of its molecules be doubled? (Ans:- 819 degree celsius)

In this article we have provided important information regarding the chapter kinetic theory of gases such as important concepts, formulae, etc.. Students should work on more solved examples and kinetic theory of ideal gas examples for securing good grades in the NEET exams.

See More

NEET 2022 exam date and revised schedule have been announced by the NTA. NEET 2022 will now be conducted on 17-July-2022, and the exam registration closes on 20-May-2022. You can check the complete schedule on our site. Furthermore, you can check NEET 2022 dates for application, admit card, exam, answer key, result, counselling, etc along with other relevant information.

See More

View All Dates

Application Form

Eligibility Criteria

Reservation Policy

Admit Card

NTA has announced the NEET 2022 application form release date on the official website https://neet.nta.nic.in/. NEET 2022 Application Form is available on the official website for online registration. Besides NEET 2022 application form release date, learn about the application process, steps to fill the form, how to submit, exam date sheet etc online. Check our website for more details.

Download full syllabus

Download full syllabus

View NEET Syllabus in Detail

All

Physics

Chemistry

Biology

See All

"NEET 2022 free online mock test series for exam preparation are available on the Vedantu website for free download. Practising these mock test papers of Physics, Chemistry and Biology prepared by expert teachers at Vedantu will help you to boost your confidence to face the NEET 2022 examination without any worries.
The NEET test series for Physics, Chemistry and Biology that is based on the latest syllabus of NEET and also the Previous Year Question Papers."

See More

NTA is responsible for the release of the NEET 2022 cut off score. The qualifying percentile score might remain the same for different categories. According to the latest trends, the expected cut off mark for NEET 2022 is 50% for general category candidates, 45% for physically challenged candidates, and 40% for candidates from reserved categories. For the general category, NEET qualifying marks for 2021 ranged from 720-138 general category, while for OBC/SC/ST categories, they ranged from 137-108 for OBC, 137-108 for SC and 137-108 for ST category.

See More

The NEET 2022 result is published by NTA on https://neet.nta.nic.in/ in the form of a scorecard on 7-Sep-2022. The scorecard will include the roll number, application number, candidate's personal details, and the percentile, marks, and rank of the candidate. Only those candidates who achieve the NEET cut-off will be considered qualified for the exam.

See More

Rank List

Counselling

Cutoff

NEET 2022 state rank lists will be released by the state counselling committees for admissions to the 85% state quota and to all seats in private medical and dental colleges. NEET 2022 state rank lists are based on the marks obtained in entrance exams. Candidates can check the NEET 2022 state rank list on the official website or on our site.

Want to know which Engineering colleges in India accept the NEET 2022 scores for admission to Engineering? Find the list of Engineering colleges accepting NEET scores in India, compiled by Vedantu. There are 1622 Colleges that are accepting NEET. Also find more details on Fees, Ranking, Admission, and Placement.

See More

FAQ

1. What is the weightage of the Kinetic Theory of gases in NEET?

Nearly 1-2 questions arise in the exam from this chapter covering about 10 marks which makes about 1 % of the total marks.

2. What are the key points that need to be practiced for solving questions from Kinetic Theory of gases?

Students should practice the numericals and learn the formulas mainly for solving the questions from the Kinetic Theory of gases.

3. Are previous year questions enough for JEE Mains?

To score 600+ in NEET, NCERT (both 11th and 12th) and previous year NEET papers are sufficient. Solving previous 10-year NEET examinations offers us a tremendous advantage because 2-3 questions with the identical alternatives are guaranteed to be repeated every year.

Trending pages