Q23 of 31 Page 94

When air is pumped into a cycle tyre the volume and pressure of the air in the tyre both are increased. What about Boyle’s law in this case?

Boyle’s law states that pressure of gas is inversely proportional to the volume occupied by gas at constant temperature and when no. of moles of gas remain constant.



As volume can be written as mass/density



So Boyle’s law is only applicable when mass of the gas remains constant.


But, when air is pumped into a cycle tyre, the mass of gas inside the tyre continuously increases and thus increases the volume and pressure of gas.


Therefore, Boyle’s law is not applicable here.


More from this chapter

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21

A gas mixture consists of molecules of types A, B and C with masses mA > mB > mC . Rank the three types of molecules in decreasing order of (a) average K.E., (b) rms speeds.

 22

We have 0.5 g of hydrogen gas in a cubic chamber of size 3cm kept at NTP. The gas in the chamber is compressed keeping the temperature constant till a final pressure of 100 atm. Is one justified in assuming the ideal gas law, in the final state?

(Hydrogen molecules can be considered as spheres of radius 1 Å).


 24

A balloon has 5.0 g mole of helium at 7°C. Calculate

(a) the number of atoms of helium in the balloon,


(b) the total internal energy of the system.


 25

Calculate the number of degrees of freedom of molecules of hydrogen in 1 cc of hydrogen gas at NTP.