Question

The answer to the question "What happens to the kinetic energy and potential energy of a solid as it melts" is that the kinetic energy stays the same and the potential energy increases. Why is this correct though?

Answer 1

its the same substance, therefore the kinetic energy is the same. The potential energy increases because it is melted and becomes a liquid. hope that helps?

Answer 2

Wait, are you sure about the answer? Kinetic energy should increase because the speed of the molecules depend on the temperature. Potential energy should decrease as the bonds between different atoms are broken?

Answer 3

Actually scratch that, kinetic energy is stable because there is no temperature during a phase shift

Answer 4

i am thinking it in another way. The intermolecular forces in solid is more than liquid. For this reason the molecules are more or less held in its position which gives its regular shape. The potential energy is due to this intermolecular force. when it changes to liquid this force reduces so the molecules are more free to move and hence no definite shape. due to this reduction in intermolecular force the potential energy decreases.But since the molecules now move more rapidly their kinetic energy increases. When the solid changes to liquid then though temp does not change but heat energy has to be supplied. This energy helps in reducing the bond between the molecules.