A substance undergoes a change of state or a phase change when a certain amount

Question

A substance undergoes a change of state or a phase change when a certain amount of heat is supplied to it. You can study the change that occurs when a substance is heated by plotting a graph of the temperature versus the during which heat is to the system. Watch the video to learn about changes of state. When a solid is heated the average kinetic energy of the particles increases allowing some of the particles to have enough energy to break away from the rigid solid structure and change to a liquid and then to a gas. You can see that in the solid phase the particle motion limited to vibrational motion: however in the gas phase molecules have long-range movement. When a solid is placed in a container and heat is applied a phase change occurs. Watch the video and identify which of the following statements are correct. Check all that apply. The average kinetic energy of the system changes while all of a solid is converted to a liquid. The temperature increases while all of a

Explanation / Answer

When there is a change of phase, specially from solid to liquid/gas, there will be a chaos geneartion in the system.

The entropy of system increases, also the order of the system ( soldi has tyically crystal lattices, which will be destroyed to form random moelcules)

Now, from the list shonw in Part A

i)

The average kinetic energy of the system changes; as heat is added, since molecules start moving randomly. this ist rue

ii)

the temprature will NOT change, since the heat energy is used to break the previous phase to the next (more chaotic) phase, i.e. solid to liquid , liquid to gas. Temperature will NOT increase as we add energy

iii)

This is false, since temperature is a direc tmeasurement of average kinetic energy of molecules, as T increases, energy increases as well

iv)

True, once again, as solid goes to liquid, temperature remains, similar as in liquid to gas transition, this is called latent heat

v) when a solid transofrm sto liquid, this implies a higher energy state, thereofre, energy must hav ebeen absorbed, this must be true

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