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These are from Lecture 5, in the actual lecture, not the end of lecture 30 minute quizzes.
To keep it brief, #97 says that NaCl is poured into a coffee cup calorimeter and the temperature in the calorimeter drops by 1 degree Celsius. It then asks what the heat of solution is after giving you some necessary data.
I figured out the amount of heat that was transferred, but the sign was important too. The answer in the back of the book says "Since the temperature went down, the reaction is endothermic with positive enthalpy." Is this backwards, or do calorimeters have a different perspective regarding system and surroundings? I took the question to mean that the solution's temperature went down, and since the solution is the system (I thought), the reaction must be exothermic.
#116 is a similar question except that in the answer it says "the reaction is exothermic because the temperature increased."
Now, am I just misunderstanding this or is the book getting it backwards?
To keep it brief, #97 says that NaCl is poured into a coffee cup calorimeter and the temperature in the calorimeter drops by 1 degree Celsius. It then asks what the heat of solution is after giving you some necessary data.
I figured out the amount of heat that was transferred, but the sign was important too. The answer in the back of the book says "Since the temperature went down, the reaction is endothermic with positive enthalpy." Is this backwards, or do calorimeters have a different perspective regarding system and surroundings? I took the question to mean that the solution's temperature went down, and since the solution is the system (I thought), the reaction must be exothermic.
#116 is a similar question except that in the answer it says "the reaction is exothermic because the temperature increased."
Now, am I just misunderstanding this or is the book getting it backwards?