2.19. Melting http://www.ck12.org
2.19 Melting
- Describe what happens to particles of matter when it melts.
- Define melting point, and state the melting point of ice.
The fiery red-orange “river” flowing downhill in this photo isn’t water. It’s molten (melted) rock, and it’s erupting
from a volcano. Most rocks on Earth’s surface are solid objects. Why is the rock that erupts from a volcano in a
liquid state? How does rock change from a solid to a liquid?
From Solid to Liquid
The process in which rocks or other solids change to liquids is called melting.Meltingoccurs when particles of a
solid absorb enough energy to partly overcome the force of attraction holding them together. This allows them to
move out of their fixed positions and slip over one another. Melting, like other changes of state, is a physical change
in matter, so it doesn’t change the chemical makeup or chemical properties of matter.
Q:The molten rock that erupts from a volcano comes from deep underground. How is this related to its liquid state?
A:It is always very hot deep underground where molten rock originates. The high temperatures give rock enough
energy to melt and remain in a molten state. Underground rock in this state is called magma.
Q:What happens to magma after it erupts and starts flowing over the surface of the ground?
A:After magma erupts, it is called lava. On the surface, lava eventually cools and hardens to form solid rock.