How long would it take a 1 200 W heater to melt 1.00 kg of ice at -12.0°C, assuming all the energy from the heater is absorbed by the ice? (Assume the specific heat of the ice is 2 090 J/kg · °C and the latent heat of fusion of water is 3.33 105 J/kg.)

Question

How long would it take a 1 200 W heater to melt 1.00 kg of ice at -12.0°C, assuming all the energy from the heater is absorbed by the ice?  (Assume the specific heat of the ice is 2 090 J/kg · °C and the latent heat of fusion of water is 3.33  105 J/kg.) 
 
what formula do you use, the fact it asks  for time, throws me off

drwls · Accepted Answer

Calculate the number of Joules of heat required (Q), using the mass, specific heat of ice, temperature rise and latent heat of fusion.

Q = M[10 C(ice) + Latent heat]
= 1.00[10*2090 + 3.33*10^5]
= 3.54*10^5 J

Then divide that by the heating rate in Watts (J/s) for the answer in seconds.

c · Answer

calculate the thermal energy required the melt 2kg of ice at 0 c. (lf=3.3x10 jkg-1)