Block of ice melts - entropy of ice?

[ally1h]

Homework Statement

A 2.00 kg block of ice at 0.0˚C melts. What is the change in entropy of the ice as a result of this process?

Homework Equations

Q = mcΔT
ΔS = Q/T

The Attempt at a Solution

Q = (2.00 kg)(2.1 kJ/kg*K)(273 K)
Q = 1092 J

ΔS = 1092 J / 273 K
ΔS = 4 J/K


Any good?

 

[Mapes]

Not good. Why would you calculate Q using an equation with ΔT? The temperature change is zero, not 273 K. I like your second equation, though, which assumes constant temperature.

How about getting the energy from the phase change?

 

[ally1h]

Then I'm not sure how to do the problem, the first part anyway, because then Q = 0 and if Q = 0 then ΔS = 0 as well...

 

[Mapes]

How about looking up the energy associated with the phase change?

 

[ally1h]

Ahhh... so I'm looking at latent heat then?
Q = mass x latent heat of fusion
Q = (2.00 kg)(333.7 kJ/kg)
Q = 667.4 kJBetter? And then plug that into the second equation?

 

[Mapes]

Better.