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Work done during isothermal expansion of one mole of an ideal gas from 10 atm to 1 atm at 300 K is (Gas constant = 2) [AIIMS 2000]
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Joule-Thomson expansion is [JIPMER 2000]
Joule-Thomson expansion is isoenthalpic.
n thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect, Kelvin–Joule effect) describes the temperature change of a real gas or liquid (as differentiated from an ideal gas) when it is forced through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment.[1][2][3]This procedure is called a throttling process or Joule–Thomson process.[4] At room temperature, all gases except hydrogen, helium and neon cool upon expansion by the Joule–Thomson process when being throttled through an orifice; these three gases experience the same effect but only at lower temperatures.[5][6] Most liquids such as hydraulic oils will be warmed by the Joule-Thomson throttling process.
The gas-cooling throttling process is commonly exploited in refrigeration processes such as air conditioners, heat pumps, and liquefiers.[7][8] In hydraulics, the warming effect from Joule-Thomson throttling can be used to find internally leaking valves as these will produce heat which can be detected by thermocouple or thermal-imaging camera. Throttling is a fundamentally irreversible process. The throttling due to the flow resistance in supply lines, heat exchangers, regenerators, and other components of (thermal) machines is a source of losses that limits the performance.
In an adiabatic expansion of an ideal gas [KCET (Med.) 2001; MH CET 2000]
q = ΔE – W, if q = 0 for adiabatic process, than ΔE = W.
For the reaction at 25°C and 1 atm. pressure, ΔH = –874 kJ. Then the change in internal energy (ΔE) is …. [Orissa JEE 2002]
For this reaction Δn = 0 than ΔE = ΔH.
One mole of an ideal gas is allowed to expand freely and adiabatically into vacuum until its volume has doubled. A statement which is not true concerning this expression is [Pb. PMT 1998]
ΔS = 0 is not true.
At 27°C, one mole of an ideal gas is compressed isothermally and reversibly from a pressure of 2 atm to 10 atm. The values of ΔE and q are (R = 2) [BHU 2001]
at constant temperature, ΔE = 0.
ΔE = q + w; q = –w = –965.84 cal.
ΔE° of combustion of isobutylene is –X kJ mol–1. The value of ΔH° is [DCE 2004]
(i.e., negative)
we know that
(∵ Δng = –ve)
∴ ΔH < ΔE
An ideal gas expands in volume from 1 × 10–3 m3 to 1 × 10–2 m3 at 300 K against a constant pressure of 1 × 105 Nm–2. The work done is [AIEEE 2004]
The spontaneous flow of heat is always
Heat is always flow from the higher to lower temperature.
Mixing of non-reacting gases is generally accompanied by
Mixing of non-reacting gases increases randomness and so increase entropy.
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