Changes in States of Matter Created by: Mrs. Susan Dube

Changes in State/Phase changes A phase describes a physical state of matter that is altered or changed by physical means, thereby creating a physical change!

Changing states of matter Solids can become liquids and liquids can become solids Liquids can become gases and gases can become liquids Solids can become gases (Copy into notes)

Melting – solid to liquid Melting is the process by which a solid becomes a liquid Melting point – is the lowest temperature at which a substance begins to melt (copy into notes)

Melting and particle arrangement As solids heat up, the particles gain energy and vibrate faster causing the particles to break loose and slide past one another becoming a liquid (copy into notes)

Freezing – liquid to solid Freezing is the process by which a liquid becomes a solid Freezing point – is the temperature at which a specific liquid becomes a solid The substance’s freezing point is the same as the substance’s melting point where the substance could exist either as a solid or a liquid (copy into notes)

Freezing and particle arrangement As a liquid’s temperature is lowered, the particles lose energy and move more slowly. Eventually, the particles move so slowly that the attraction among them cause the liquid to become a solid (copy into notes)

Check for Understanding What are the ways in which a solid can change state into a liquid or that a liquid can change into a solid? (answer question in notes)

Evaporation – liquid to gas Evaporation is the process by which a liquid becomes a gas Evaporation usually occurs at the surface of a liquid The fastest moving particles at the surface of the liquid break away from the liquid and become gas particles (Copy into notes)

Evaporation and particle arrangement As the temperature increases, the energy in the liquid increases and the movement of the particles increases allowing them to escape from the liquid and become a gas (Copy into notes)

Boiling – liquid to gas Boiling is another process by which a liquid becomes a gas Boiling point – is the temperature at which the liquid becomes a gas Substances have specific boiling points Ex. Water boils at 100⁰C or 212⁰F (Copy into notes)

Check for understanding What are the ways in which a liquid changes state into a gas? What happens to the particles during that phase change? (Answer question in notes)

Boiling and particle arrangement As the temperature increases, the energy in the liquid increases and the movement of the particles increases allowing them to escape from the liquid and become a gas (Copy into notes)

Sublimation – solid to gas Sublimation is when a solid changes directly to a gas (Copy into notes) Ex. Dry ice is frozen carbon dioxide that sublimates

Condensation – gas to liquid Condensation is the process by which a gas becomes a liquid Copy into notes

Condensation and particle arrangement When you cool a gas, the particles move more slowly and the attraction between the particles increases pulling the particles closer together forming a liquid (copy into notes)

Check for understanding How does sublimation differ from condensation? (Answer question in notes)