posted by I on .
An open container holds ice of mass 0.540 kg at a temperature of -18.7 c The mass of the container can be ignored. Heat is supplied to the container at the constant rate of 790 J/minute.
The specific heat of ice to is 2100 J/kg . K and the heat of fusion for ice is 334 * 10^3 J/kg.
A) How much time passes before the ice starts to melt?
B) From the time when the heating begins, how much time does it take before the temperature begins to rise above 0 C?
Q1 = cmΔ= 2100•0.54•18.7 = 2.12•10^4 J.
Q2 = r•m = 334•103•0.54= 1.8•10^5 J.
Q1/q = 2.12•10^4/790 = 26.8 min – 0.45 h.
(Q1+Q2)/q = (2.12•10^4 + 1.8•10^5)/790 = 255.1 min = 4.25 h.