Wednesday, May 18, 2011

Isothermal Reversible Expansion Work of an IDEAL Gas

Consider an ideal gas confined in a cylinder with a frictionless piston. The reversible
expansion of gas takes place in a finite number of infinitesimally small
intermediate steps. If the Pext is infinitesimally less than internal
pressure of gas ‘P’ by ‘dP’. Then gas expands reversibly and piston moves
through a distance ‘dl’.              
Since dP is so small, for all practical purposes.                              
Pext.  – Pgas  = P.              
One work done by gas in one infinitesimal step (dw) can be expressed as;                              
dw   =   P  ´  dV.         [ w = P ´ DV]                        
\dw  =   PdV.                            
If the gas expands from V1 to V2 during isothermal
reversible expansion. The total amount of work done would be equal to

12 comments:

  1. Replies
    1. there will apear an n in the last expression only which shows that the moles are n in number

      Delete
  2. This comment has been removed by the author.

    ReplyDelete
  3. What if no of moles remains same

    ReplyDelete
    Replies
    1. remove the n from the last expression so the resultant answer will be the answer to you question

      Delete
  4. what will be the enthalpy change

    ReplyDelete
    Replies
    1. For a substance of fixed composition, the enthalpy changes with change in temperature at constant pressure, can be calculated as.....
      Delta H= Integral Sign(a+bT+bT^-2) and Limits of integrals are T1 to T2

      Delete
  5. what will be the enthalpy change

    ReplyDelete
    Replies
    1. For a substance of fixed composition, the enthalpy changes with change in temperature at constant pressure, can be calculated as.....
      Delta H= Integral Sign(a+bT+bT^-2) and Limits of integrals are T1 to T2

      Delete
  6. Replies
    1. W is +ve when the work is done ON the system by the surroundings.

      Delete
  7. When to use -nRT ln v2/v1 and -2.303nRTlogv2/v1

    ReplyDelete