Why are these the answers This is my work Delta Sunivese = delta Ssys + delta Ss

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Why are these the answers

This is my work

Delta Sunivese = delta Ssys + delta Ssur

Delta G = Delta H - T delta Ssys

The temperature decreses so, the reaction is endothermic meaning delta H is + , T is + , delta S surounding = -deltaH/T = - , The solid dissolves, so delta S system is + ,

Delta G = ? Delta S = ? Since, delta S system is + and delta S surrounding is -, I don't see how we can guess Delta G and Delta S' sign. Please explain. How do we know that delta S surrounding is less than Delta S system?

7. A 100 mL sample of water is placed in a coffee cup calorimeter. When 1.0 g of an ionic solid is added, the temperature decreases from 21.5°C to 20.8 oC as the solid dissolves. For the dissolving of the solid, True or False? a) the surrounding gets hotter F 0 univ c) Sys 0 d) Surr 0 F e) AS sys Surr ASun sys Sur 8. Predict the sign of AS

Explanation / Answer

(7)

(a) The surroundings get hotter - False - Since energy is absorbed by the system surroundings get colder.

(b) delta Suniv > 0 - TRUE - Dissolving of ionic compound is spontaneous one, hence entropy of universe is positive.

(c) delt Ssys < 0 - False - Since ionic compound is being dissolved, entropy of the system increases

(d) delta Ssurr > 0 False - Since energy from surroundings is absorbed by system, hence entroy of surroundings decreases

(e) delta Ssys < delta Ssurr - False - inorder to occur a spontaneous reaction entropy of universe should be positive.

delta Suniv = delta Ssys + delta Ssurr

we know, for the present system, delta Ssys = +ve and delta Ssurr = -ve,

to keep delta Suniv postive, delta Ssys > delta Ssurr

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