[plu]

Hello,

This is a question about supercooled water that I am having trouble on:

Data: C_p(ice) = 76.1 J/K mol    C_p(water) = 37.15 J/K mol    dH_fus(H₂O) = 6.01 kJ/mol

Consider 28.5 g of supercooled (liquid) water at -12.0 ^oC and 1.00 bar.  This metastable state suddenly freezes to ice at the same temperature and pressure.

(i) Treating the metastable state as an equilibirum state, calculate the heat released in this process.

     This I calculated to be 1.58 mol x 6.01 kJ/mol = 9.51 kJ

(ii) What is the change in entropy of the system?

     I am not sure here.  I figured that the energy released from the sudden fusion of the water would be applied to the newly-formed ice to heat it up to 0 ^oC .  Then, since dS = nC_pln(T₂/T₁) at constant pressure, dS would equal 5.4 J/K mol...?

(iii) Assuming the temperature of the surroundings is -12 ^oC, what is the change in entropy of the surroundings?

     Would this simply be dS_sur = q_p / T = -23 J/K mol ?  However, this wouldn't make sense since then dS_system + dS_sur < 0  

[gregpawin]

i think you use the equation you used for part 3 for part 2

[plu]

i think you use the equation you used for part 3 for part 2

I do not think this would work since temperature is not constant and thus only the inequality dS > q_p/T is true