Pressure of 1 g of an ideal gas A at 27 | Class 11 Chemistry Chapter States of Matter, States of Matter NCERT Solutions

Question:

Pressure of 1 g of an ideal gas A at 27 °C is found to be 2 bar. When 2 g of another ideal gas B is introduced in the same flask at same temperature the pressure becomes 3 bar. Find a relationship between their molecular masses.

Answer:

Mass of gas A , WA = 1g

Mass of gas B,  WB = 2g

Pressure exerted by the gas A = 2 bar

Total pressure due to both the gases = 3 bar

In this case temperature & volume remain constant

Now if MA & MB are molar masses of the gases A & B respectively,therefore

pA V= WA RT/MA & Ptotal V = (WA/MA + WB/ MB) RT

= 2 X V = 1 X RT/MA & 3 X V = (1/MA + 2/MB)RT

From these two equations, we get

3/2 = (1/MA + 2/MB) / (1 /MA) = (MB + 2MA) / MB

This result in 2MA/ MB = (3/2) -1 = ½

OR MB = 4MA

Thus, a relationship between the molecular masses of A and B is given by

4MA = MB   


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Comments

  • Sana
  • 2019-10-17 20:34:13

Why it can't be just p directly proportional to molecular weight by which mw1=2mw2


  • Rockstar
  • 2019-09-20 22:45:27

Greatest explanation


  • Samadrita
  • 2019-06-27 21:06:26

Thank you. Really helpful 😀


  • Lakshita joshi
  • 2019-02-27 12:22:22

R is here universal gas constant


  • Lakshita joshi
  • 2019-02-27 12:21:59

R is here universal gas constant


  • Niti
  • 2018-11-08 15:30:29

Why does the volume is constant here ... it is not given in question ..????


  • shiva tiwari allhabadi
  • 2018-10-30 07:16:11

W means n


  • shiva tiwari allhabadi
  • 2018-10-30 07:15:55

R means 0.281 atm


  • shiva tiwari allhabadi
  • 2018-10-30 07:11:34

Anita are u know the formula of mAss\molarmass =n and here n is represented by W 😕😕


  • Anita
  • 2018-08-13 22:08:58

What is meaning of wA/mA+wB/mB in this question please answer


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 11 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 5: Pressure of 1 g of an ideal gas A at 27 °C is found to be 2 bar. When 2 g of another ideal gas B....