Question

derive an equation to explain the concept of fugacity in non ideal gas

Answer 1

Expression for fugacity of a real gas Fugacity is a measure of the free energy of a non-ideal gas for an rent ideal gas, the molon - aibba free energy, also defined as the t. Chemical potential (4) is given by :.. M = 'u' (T) + Rt en p u where a = chemical potential i of the standard 1 For a non-ideal gas, the sia state above above equation ? exualion is p = pressure changed. is changea ulo t t e 9 to; a= MORT) + Rien of (where f= fugacity) ... (1) Thus, fugacity of a non-ideal gas in can be conceived to the wont bear same significance as presa une has on ideal gas 9 птър •hive of modu of 4 мм; wе may write; A = H-TS H = Enthalpy & 0 5 . En troby differentiating, € = internal energy da dH - Tds & SdJ in eil 1 orda = df Pdv + vdp - Tds asdT. I de TQ - Pdv, is Ar. da= law] to & Vd P - Tds asdt = ds, and law] or, da = Ads & vdp. Tasos

Sdt .... lol i dai vidp- sdt ....(") At constant temperature T w dt = 0 ..da: for each vd p mole dpt r ehite of the negaus Ñ i moln volume of real gas da Or, du vdp [ from definition; du da 1 sida. Vid - molar volema for ideal gas de Subtracting anda rating these two i hora dood gl u tenant dcu - uid) ( v . v id) db Integrating from top we get bo to p; "O qu-uid) -(6-mid) + Mür vid ) abs from earlier discussion, uiduidat Rtemp e u no & Ri en ff 20ů Instan nomorot- Putting these values we obtain RT ( en f- enp) f. - Vid) d. p we we set; b. ( very low pressure] en fa enpt I Il-Bid) de i knowing (void)/Rt as a function of pressure and plotting we can calculate fit .

Another form of this equation is derived by accounting compressibility factor; ²= /vid a en fa en pt at l (7-1) db (simplified form)