Question

1. An ice cube weighing 18g is removed from a freezer, where it has been at -20oC.

a. How much heat is required to warm it to 0oC without melting it?

b. How much additional heat is required to melt it to liquid water at 0 oC?

c. Suppose the ice cube was placed initially in a 180 g sample of liquid water at +20 oC in an insulated (thermally isolated) container. Describe the final state when the system has reached equilibrium.

Answer 1

334J/g Heat of Fusion

2260J/g Heat of Vaporization

2.1J/g°c Heat capacity of solid water

4.18J/g°c Heat capacity liquid water

a. How much heat is required to warm it to 0oC without melting it?

q=mCΔT
q=heat energy gained or lost by a substance
m=mass (grams)
C=specific heat
ΔT=change in temperature

Q= 18 x 2.1 x (20) = 756 J is required

b. How much additional heat is required to melt it to liquid water at 0 oC?

Q = 756 + 18 x 334 J = 6768J is required

c. Suppose the ice cube was placed initially in a 180 g sample of liquid water at +20 oC in an insulated (thermally isolated) container. Describe the final state when the system has reached equilibrium.

6768 = 180 x 4,18 (20-T_f)

8.99 = (20-T_f)

T_f = 20-8.99 = 11⁰C