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24 Feb 2008 19:41:04 IST

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What do negative entropies signify?

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What do negative entropies signify?

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Chirag Sangani

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24 Feb 2008 19:51:28 IST

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Aqueous solutions of certain compounds eg. Calcium hydroxide have a negative standard entropy (S, not delta S). What does negative entropy of a substance signify physically, considering the fact that perfect crystalline solid lattices at 0 K are assigned 0 entropy.

LAMPARD

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26 Feb 2008 16:54:07 IST

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The third law of thermodynamics ststes dat entropy of a perfect crystalline solid is 0 at 0K.All chemical compounds therfor hav standard entropies dat r +ve.But those associated wid ions maybe -ve bcoz of the convention of regardin de std. entropy of the hydrated proton as 0,n bcoz dey inc. de effect of hydration process on the water molecules in their co-ordination spheres.
Boltzmann gav an eqn.
S=k*ln(W),where W is the thermodynamic probability of state of system.Now a crystalline solid at 0 K is considered 2 be in its most ordered state.In this case,W=1 n hence S=0 acc. 2 boltzmann eqn...
u may not understand dis as its in 12th ISC buk...

Chirag Sangani

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26 Feb 2008 17:23:06 IST

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yeah i understood that the thermodynamic probability of a perfect solid is 1 as it can have only 1 possible state. So what abt ions? Since a hydrated proton has 0 entropy (only 1 possible state) dissolved ions like OH- will have greater entrnpy, according to me. Cud u pl. Explain

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