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AP EAMCET202125 Aug 2021Morning ShiftChemistryThermodynamics (C)Actual

The boiling point of water at 1 ~atm is 100^ C . Which among the following is true for vaporisation of water at 75^ C ?

Options

  1. AG_ vap ^ >0
  2. BH_ vap ^ < 0
  3. CK_ vap =1
  4. DS_ vap ^0 < 0

Correct answer

A. G_ vap ^ >0

Step-by-step solution

According to standard Gibbs free energy equation i.e., aligned & G^ = H^ -T S^ & G^ =-T S^ & G^ -T aligned It means G^ is inversely proportional to temperature due to negative sign present in Gibbs free energy equation. Hence, lesser the temperature i.e., 75^ C , greater the value of ^ G_ vap ( G_ vap ^0>0 ) . At 100^ C , G_ vap ^0 value is lesser than that at temperature 75^ C . Vaporisation of water at 75^ C has G_ vap ^ >0 .

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