Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Matter is defined as anything that occupies space, has mass, and can be perceived by our senses. It is composed of tiny particles called atoms or molecules.
The Kinetic Molecular Theory of matter states that particles are in continuous random motion and possess kinetic energy.
Intermolecular Space (): The empty space existing between the molecules of a substance. It is minimum in solids and maximum in gases.
Intermolecular Force of Attraction (): The force with which molecules attract each other. It is strongest in solids and weakest in gases.
Solids: Have a definite shape and a definite volume. Molecules are closely packed with negligible .
Liquids: Have a definite volume but no definite shape (they take the shape of the container). Molecules are less closely packed compared to solids.
Gases: Have neither a definite shape nor a definite volume. They exhibit maximum fluidity and are highly compressible as is very large.
Change of State: The process by which matter changes from one physical state to another by absorbing or releasing heat energy, such as melting (Solid to Liquid) or sublimation (Solid to Gas).
Water exists in three states: Ice (Solid), Water ( Liquid), and Water Vapor ( Gas).
📐Formulae
💡Examples
Problem 1:
A solid block of iron has a mass of and occupies a volume of . Calculate its density in .
Solution:
Explanation:
Density is the ratio of mass to volume. By dividing the given mass () by the volume (), we find the density of iron.
Problem 2:
Why does a gas fill the entire space of the vessel it is placed in?
Solution:
In gases, the Intermolecular Force () is almost negligible and the Intermolecular Space () is very large.
Explanation:
Because the particles have high kinetic energy and weak attractive forces, they move freely in all directions to occupy all available space.
Problem 3:
Identify the process when Naphthalene balls disappear over time without leaving any residue.
Solution:
Sublimation
Explanation:
Sublimation is the process where a solid directly converts into a gas upon heating (or at room temperature) without passing through the liquid state.