Chapter 9 Homework Using the Law of Conservation of Energy e previous 3 of 11 l
ID: 695789 • Letter: C
Question
Chapter 9 Homework Using the Law of Conservation of Energy e previous 3 of 11 l ned Part A Using the Law of Conservation of Energy How much boiling water would you need to raise the bath to body temperature (about 37Cy? Assume that no heat is transferred to the surrounding environment Express your answer to two significant figures and include the appropriate units. Imagine that your water heater has broken, but you want to take a bath. You till your bathtuo with 25 kg of room-temperature water (about 25 C). You figure that you can boil water on the stove and pour it into the bath to raise the temperature Hints 4.8 kg Submit My Answers Give Up Correct Significant Figures Feedback: Your answer 4.7619 kg was either rounded diferently or used a different number of significant figures than required for this part Part B The amount of boiling water required to raise the temperature of 25.0 kg of water in the bath to body temperature is 4.80 kg. In this process, the heat lost by the boiling water is equal to the heat gained by the room-temperature water. How much heat was transterred in this process? Express your answer to four significant figures and include the appropriate units Hints 1300 KJ Submit My Answer Give Up Incorrect; Try Again; 2 attempts remaining; no points deducted One or more of the units you entered is not recognized. Click help to view a list of recognized unitsExplanation / Answer
Ans. The temperature of boiling water = 100.00C
The final temperature of boiling water cooled to = 37.00C
Now,
The amount of heat released by boiling water to cool down is given -
q = m s dT
Where,
q = heat
m = mass
s = specific heat
dT = Final temperature – Initial temperature
Putting the values in above reaction-
q = 4.80 kg x (4.184 kJ kg-10C-1) x (37.00C – 100.00C)
Or, q = -1265.24 kJ
The –ve sign of q indicates that heat is being released when boiling water cools.
# The total amount of heat lost by 4.80 kg boiling water is gained by 25.0 kg colder water. For reaching thermal equilibrium, the boiling water transfers 1265.24 kJ heat to the colder water.