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from destroyer #172 (2010)
Ammonium nitrate will dissolve in water at 25oC, and a decrease in temperature is noted. Which of the following is true?
A. -delta H; +delta S
B. -delta H; -delta S
C. +delta H; +delta S
D. +delta H; -delta S
E. +delta H; delta S=0
Ans: C.
Ok, i understand that as u dissolve a substance then deltaS>0. So that rules B, D, E. Leaving us with A and C. I don't understand how decreasing the temp would make deltaH>0. Because if you decrease the temp, for i.e: going from liquid to solid it's exothermic. so how, in this case, can delta H be positive if we decrease the temp?
Ammonium nitrate will dissolve in water at 25oC, and a decrease in temperature is noted. Which of the following is true?
A. -delta H; +delta S
B. -delta H; -delta S
C. +delta H; +delta S
D. +delta H; -delta S
E. +delta H; delta S=0
Ans: C.
Ok, i understand that as u dissolve a substance then deltaS>0. So that rules B, D, E. Leaving us with A and C. I don't understand how decreasing the temp would make deltaH>0. Because if you decrease the temp, for i.e: going from liquid to solid it's exothermic. so how, in this case, can delta H be positive if we decrease the temp?
