Using the values for the heat fusion, specific heat of water, and/or heat of vap
ID: 893134 • Letter: U
Question
Using the values for the heat fusion, specific heat of water, and/or heat of vaporization, calculate the amount of heat energy in each of the following: a) joules released when 125g of steam at 100 degrees Celsius condenses and cools to liquid at 15.0 degrees Celsius. b) kilocalories needed to melt a 525g ice sculpture at 0 degrees Celsius and to warm the liquid to 15.0 degrees Celsius. c) kilojoules released when 85.0g of steam condenses at 100 degrees Celsius, cools, and freezes at ) degrees Celsius.
Explanation / Answer
a) joules released when 125g of steam at 100 degrees Celsius condenses and cools to liquid at 15.0 degrees Celsius
molar heat of vaporization for water DHvap = 40.7 kJ/mol.
no of moles of water = 125/18 = 6.94
s= specific heat of water = 4.18 j.k-1.g-1
q released = n*DHvap + mwater*s water *DT
q released = ((6.94)40.7)+(125*4.18*(100-15)
= 44.69 kj
b )
DHfus of ice = 6.02 kJ/mol
Qabsorbed by converting ice to water = n*6.02 + m*s*Dt
= ((525/18)*6.02)+(525*4.18*(15-0))
= 33.09 kj
c) incomplete data
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