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For the reaction $2 Cl left parenthesis straight g right parenthesis space rightwards arrow space space Cl subscript 2 left parenthesis straight g right parenthesis comma$ what are the signs of $increment straight H space and space increment straight S.$ ?

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Long Answer Type

252.

Prove that in a reversible process:
∆_(system) ⁺ ∆S_{(surroundings)} = 0
Or
Prove that there is no net change in entropy in a reversible process.

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253.

Prove that in an irreversible process:
∆S_(system) + ∆S_{(surroundings)}> 0

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254.

What do you understand by:
(i) The entropy of fusion?
(ii) The entropy of vapourisation ?

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Short Answer Type

255.

You are given normal boiling points and standard enthalpies of vapourisation. Calculate the entropy of vapourisation of liquids listed below:
Liquid $straight b. straight p. space left parenthesis degree straight C right parenthesis space space space space space space space space space increment straight H subscript vap superscript 0 space end superscript space left parenthesis kJ space mol to the power of negative 1 end exponent right parenthesis$
$space left parenthesis straight a right parenthesis space Ethanol with left parenthesis straight C subscript 2 straight H subscript 5 OH right parenthesis below space space space space space space space space space space space space space space space space space space 78.4 space space space space space space space space space 42.4 space left parenthesis straight b right parenthesis space Toluene with left parenthesis straight C subscript 2 straight H subscript 5 CH subscript 3 right parenthesis below space space space space space space space space space space space space space space space space space space 110.6 space space space space space space space 35.2 space space$

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256.

Calculate the entropy change of n-hexane when 1 mole of it evaporates at 341.7 K(∆H_vap = 29.0 kJ mol^–1).

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257. When one mole of a solid ‘S’ (molecular weight 46) at its melting point is changed into the liquid at the same temperature, an entropy change of 26.4 JK^–1takes place. Calculate the melting point of the solid if its enthalpy of fusion is 0 .1 kJg^–1.

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258. Calculate the entropy change in surroundings when 1.00 mol of H₂O(l) is formed under standard conditions. ∆_fH⁰ = –286 kJ mol^–1.

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Long Answer Type

259.

What are the two tendencies which determine the feasibility of process? How are the two related to each other?

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260.
What is free energy? Prove that ∆G = ∆H – T∆S.

Free energy is a thermodynamic quantity and refers to the capacity of the system to do useful work. It may be defined as the amount of energy available from a system that can be put into useful work. Mathematically, free energy (G) is defined by the relation:

G = H - TS ...(1)

where H is the heat content. T is absolute temperature and S is the entropy of the system.
H = U + PV