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AP EAMCET20226 Jul 2022Evening ShiftChemistryThermodynamics (C)Actual

For a reaction to be spontaneous, the required conditions are

Options

  1. A_r H^ =- ve, _r S^ =- ve, at high T .
  2. B_r H^ =+ ve, _r S^ =+ ve, at high T .
  3. C_r H^ =+ ve, _r S^ =+ ve, at low T .
  4. D_r H^ =+ ve, _r S^ =- ve, at all T .

Correct answer

B. _r H^ =+ ve, _r S^ =+ ve, at high T .

Step-by-step solution

Depending upon the sign and magnitude of H and -T S , the sum of these terms determines the sign of G . This sign of G will determine i.e. if G is negative then the reaction is spontaneous and if G is positive then the reaction is non-spontaneous. array |c|c|c|c|c| H & S & -T S & G & Spontaneous/ Non-spontaneous + & - & + & + & Non-spontaneous - & + & - & - & Spontaneous - & - & + & & array l Spontaneous at low T Non-spontaneous at high T array + & + & - & +o r & array l Non-spontaneous at low T Spontaneous at high

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