January 2020 NY Regents Chemistry Exam
13 What is the amount of heat released by 1.00 gram of liquid water at 0°C when it changes to 1.00 gram of ice at 0°C?
(1) 4.18 J
(2) 273 J (3) 334 J
(4) 2260 J
Solution: When water changes from liquid to solid phase (ice), we use Heat of fusion in our calculations. All of the heat equations can be found on Table T in the Reference Table. An equation that involves heat of fusion is q = mHf where q=heat and Hf =heat of fusion. Mass is 1.00 gram according to the question.
Heat of fusion of water can be found in Table B and is 334 J/g. Now, we can plug everything in
q=1.00 g*334 J/g
Answer:3
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