Question

An ice cube sitting in the open air and it is melting. Consider the system is the ice cube and its meltwater.

1) Is the object is absorbing or giving off heat? Why?

2) Is the object's temperature increasing or decreasing? Why?

3) Is the object's internal energy increasing or decreasing? Why?

4) Is the object is doing mechanical work or having work done on it? Why?

5) Is the object's entropy increasing or decreasing? Why?

Answer 1

since ice cube is started melting ,it takes heat energy without changing it's temperature

so answers are

1) absorbing ,to break the bonds in ice to melt

2) it's simply phase changing ,so all supplied heat energy used for change of phase and not to increase the temperature ,so T remains constant

3) since internal energy is a function of temperature ,T is constant hence there is no change in internal energy

4) since the system was absorbing heat energy ,so object is doing mechanical work

5) change in entropy ds = dQ/T

since heat absorbed(dQ) is positive ,hence change in entropy is also increasing