When a cup of hot chocolate is heated from 80 C to 90 C, which of the following is happening to the molecules of the liquid?

a
The motion of the molecules will stay the same.
b
The motion of the molecules will stop.
c
The motion of the molecules will speed up.
d
The motion of the molecules will slow down.

1 answer

c) The motion of the molecules will speed up.

When heat is added to a substance, the kinetic energy of its molecules increases, causing them to move faster and collide more frequently. As a result, the temperature of the substance increases. So, when a cup of hot chocolate is heated from 80 C to 90 C, the motion of the molecules will speed up.