1. The problem statement, all variables and given/known data A 100 g mass of supercooled water at -2ºC in thermal contact with surroundings also at -2ºC freezes spontaneously. Calculate the entropy change of the universe assuming that the surroundings act as a large temperature reservoir. [The specific heat capacity of ice is 2090 J kg-1 K-1, the specific heat capacity of water is 4183 J Kg-1 K-1, and the latent heat of fusion of water is 334.7 kJ kg-1.] Is this process reversible? 2. Relevant equations Change in entropy of the universe = change in entropy of the system + change in entropy of the surroundings dS = dQ/T (for a reversible process) 3. The attempt at a solution latent heat of fusion = l = 334700J/Kg T2 = freezing temperature of water = 273K T1 = -2 degrees Celcius = 271K mass = m = 0.1Kg Change in entropy of the system = (-)m*l/T2 = (0.1*334700)/273 = -122.60J/K Change in entropy of the surroundings = (+)m*l/T1 = (0.1*334700)/271 = 123.51J/K Change in entropy of the universe = 123.51 -122.60 = 0.9J/K The process is irreversible I have a feeling this is wrong because i haven't used the heat capacities of ice and water (not sure how to) any help would be appreciated, thanks.