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Homework answers / question archive / A 46
A 46.6-g sample of warm water was combined with a sample of liquid nitrogen in a Styrofoam cup calorimeter. The liquid nitrogen sample rapidly evaporated, leaving only cool water in the calorimeter. Careful temperature measurements showed that the water cooled from an initial temperature of 74.60 C to a final temperature of 8.50 C. Calculate the amount of heat released by the water. Express your answer in units of kilojoules.
Answer:
We use Heat energy = c*m*?T
Q = 4.18 J/(g*°C)*46.6 g *66.1 °C = 12875.49 J
Q= 12.89 kJ
Here we are required to calculate the amount of heat released by the water not heat absorbed by liquid nitrogen. And heat released is taken as positive that's why Q is positive.
