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i got a problem im stuck with and it'll probably be easy for you but i cant figure it out for some reason... It has to do with heat transfer and latent heat...

A tank containing 740 kg of water cools from 15 degrees to 0 degrees and completely freezes. What is the total heat given off? How many hours would a 1.2 kW eletric heater have to work to provide the equivilant heat the water gives off? (The heater provides 1.2 x 10^3 J/s of heat)

thanks

heres my work:

for part 1: Q=mcT

Q= (740kg)(4200 J/ kg C)(0 degrees- 15 degrees) 9specific heat capacity for water= 4200 J/kg C

= -46 620 000 J

Q= LfM

Q= (3.3x10^5 J/kg)(740 kg)

Q= 244 200 000 J

Total heat= -46 620 000J + 244 200 000J

=197 580 000

book says answer is 2.9 x 10^8 (with S.d.) I know how to do the second part but its this first part messing me up....

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