chapter 9 : thermal properties of matter

Question 1

what does internal energy consist of and what do they do ?

Answer 1

• internal potential energy : amount of potential energy stored in the bonds depends on the forces between the particles and how far apart they are.
• internal kinetic energy : due to the motions of particles , it is directly related to the temperature ; the higher the temperature , the more vigorous the motion of particles.

Question 2

what is melting ?

Answer 2

the process whereby energy supplied changes the state of a substance from a solid state to a liquid state without a change in temperature

Question 3

what is boiling ?

Answer 3

the process whereby energy supplied changes the state of substance from liquid state to gaseous state without a change in temperature

Question 4

when solid melts … …

Answer 4

Thermal energy is absorbed to overcome the forces of attrction between the particles. Only the total internal potential energy increases and since the total kinetic potential energy does not increase , the temperature does not change while its melting

Question 5

when solidification occurs … …

Answer 5

During solidification , the particles move closer together as the forces of attraction becomes stronger. Due to thermal energy being released and lost into the surrounding air , the internal potential energy decreases and since the total kinetic potential energy does not decrease , the temperature does not change throughout solidification