Gas Laws - 7

Q. ends. Its lies …… sum containg Hg & two equal ends containing air at same pressure P_o. When tube is held at < 60⁰ with vertical, length of air column above & below mercury are 46 & 44.5 cm respectively. Calculate pressure P_o in cm of Hg.
Ans:

Let ......., length of air column is L cm.
2L + 5 = 45 + 5 + 44.5
L = 45.25 cm
When tube is held vertically at 60⁰, Hg will dispalce to lower end.
P_B + 5 cos60 = P_A ................................... (i)



Dumb Question: Why equation (i) holds ?
Ans: Pressure at lower end is equal to pressure at upper end plus effective pressure due to mercury.
P_A - P_B = 5 x = 2.5 cm of Hg ............................... (i)

For end A:

    
=> P_A = x P_o ........................................... (ii)
For end B:

    
=> P_B = x P_o .......................................... (iii)
By equation (i), (ii) & (iii)
     P_o = 75.4 cm of Hg.

Q. are filled to pressure of 2 atm, one with 14 Kg N₂ & other with 1 Kg of H₂. N₂ ballon leaks to pressure of atm in 1 for. How long will it take for H₂ balloon to reach a pressure of atm ?
Ans: At constant V & T, for a gas P W

Dumb Question: How P T at constant V & T ?
Ans: PV = nRT
As V & T or constant
      P n    => P
=> P W     ( Mol. Mass)
For N₂, P₁ = 2 atm        P₂ = atm        time t = 1 hr
     W₁ = 14 Kg, W₂ = ?


wt. of N₂ deffused =
For H₂, P₁ = 2 atm, P₂ = atm, t = t hr
     W₁ = 1 kg,     W₂ = ?

    
Wt. of H₂ diffused = 1 -
    
Moles of H₂ diffused =


t = 60 x = 16 mus.

Keywords:

* Boyle's Law
* Charle's Law
* Avogrado's Law
* Ideal Gas Equation
* Dalton's Law
* Aqueous Tension
* Partial Pressure
* Graham's Law
* Diffusion/Effusion
* Kinetic Gas Equation
* Most Probable Speed
* Root mean Square Speed
* Average Speed
* Compressibility factor
* Vander Waal's Equation
* Critical Temperature
* Critical Pressure
* Critical Volume