P3 : Heating and Cooling Graphs

Question 1

Internal energy

Answer 1

Energy stored inside a system by the particles
This include the kinetic energy and the potential energy of the particles

Question 2

What do scientists call the energy needed for a substance to change state

Answer 2

Latent heat

Question 3

Change of state

Answer 3

During the change of state we are increasing the internal energy store of the system but we are not changing the temperature
When the substance changes state the temp stops increasing and becomes constant (on a graph)

Question 4

Melting point

Answer 4

Temperature the substance melts at

Question 5

Heating graph

Answer 5

. Temperature of the solids rise as we are increasing internal energy of the particles
. At some point the temperature stop rising and the line becomes horizontal
. At this point the solid is changing state and turning into a liquid
. The energy we are putting in is weakening or breaking the forces of attraction between the particles allowing the substance to change from a solid to a liquid
. Eventually all of the solid will have melted into a liquid and the temperature starts to rise again
. That is because we are increasing the energy of the particles
. The line becomes horizontal again and the substance is boiling. The energy we are putting in is weakening or breaking the forces of attraction between particles
. Once all the liquid has boiled the temp starts to rise again

Question 6

Cooling graph

Answer 6

. When the gas changes to a liquid this is called condensation
. When the liquid changes to a solid this is called freezing