Question

Amount of thermal energy needed to change 50g of ice at -20 degrees Celsius to water at 10 degrees Celsius? Thanks for any help (:

Answer 1

heat of fusion of water = 334 J/g
heat of vaporization of water = 2257 J/g
specific heat of ice = 2.09 J/g·°C
specific heat of water = 4.187 J/g·°C


You need to calulate the thermal energy needed to bring 50g of ice from -20C to 0 C, and then heating the 0C water to 10C.

q = mcΔT

q= energy, m=mass, c=thermal capacity, ΔT=change in temp.
\[50g*2.09J/g°C*[0°C--20°C]=2090 joules\]
Heat required to convert ice to water is q = m·ΔHf; where ΔHf is the heat of fusion of water.
q=50g*334J/h = > 16700 joules

and finally the heat required to change the 0C water to 10C.

q = mcΔT ;
q = 50g * 4.18 J/g·°C * (10C-0C) = 2090

add the total up..
2090+16700+2090 = 20880 Joules