Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Matter exists in three primary states: Solid, Liquid, and Gas, determined by the space and forces of attraction.
Melting (Fusion): The process of changing a solid into a liquid state by heating. The constant temperature at which this occurs is called the Melting Point (e.g., for ice).
Vaporization: The process of changing a liquid into a gas. It occurs in two ways: Boiling (at a fixed ) and Evaporation (at any temperature below the boiling point).
Condensation: The process by which a substance in the gaseous state changes into its liquid state upon cooling.
Freezing (Solidification): The process of changing a liquid into a solid by cooling. For pure water, the freezing point is .
Sublimation: The direct change of a solid into a gas without passing through the liquid state. Common substances include (Ammonium Chloride), Camphor, and Naphthalene.
Deposition: The reverse of sublimation, where a gas changes directly into a solid upon cooling.
Kinetic Theory of Matter: When heat is supplied, the kinetic energy of molecules increases, increasing the space and overcoming the force of attraction.
📐Formulae
💡Examples
Problem 1:
Why does the temperature remain constant at while a block of ice is melting, even though heat is being supplied?
Solution:
This is due to the absorption of .
Explanation:
The heat energy supplied is used to overcome the forces of attraction between the ice molecules to change the state from solid to liquid, rather than increasing the temperature of the substance.
Problem 2:
Identify the process when wet clothes dry under the sun.
Solution:
The process is .
Explanation:
Water molecules at the surface of the wet cloth gain enough energy from the surroundings to escape into the air as water vapor () at a temperature below the boiling point.
Problem 3:
What happens to the space when steam condenses into water?
Solution:
The space decreases.
Explanation:
During condensation, heat is released, causing the molecules to lose kinetic energy. They move closer together, and the forces become stronger, turning the gas into a liquid.