Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Matter is made of tiny particles (atoms or molecules). The kinetic theory of matter states that these particles are in constant motion.
In a , particles are packed closely together in a regular arrangement (a ). They vibrate about fixed positions but do not move from place to place.
In a , particles are close together but arranged randomly. They have enough energy to slide past each other, which allows liquids to flow and take the shape of their container.
In a , particles are very far apart and move rapidly and randomly in all directions. Gases can be compressed because of the large between particles.
Phase changes occur with the addition or removal of energy: (solid to liquid), (liquid to solid), (liquid to gas), and (gas to liquid).
Density is a measure of how much mass is contained in a given volume: . Solids generally have the highest density, while gases have the lowest.
📐Formulae
💡Examples
Problem 1:
A sample of unknown liquid has a mass of and occupies a volume of . Calculate the density of the liquid.
Solution:
Explanation:
The density is calculated by dividing the mass () by the volume (). In this case, divided by gives .
Problem 2:
Compare the compressibility of (ice) and (steam).
Solution:
is highly compressible, whereas is virtually incompressible.
Explanation:
In , the water molecules are far apart with significant space between them, allowing them to be pushed closer. In , the molecules are already in a fixed, close-packed structure with no room to move closer.
Problem 3:
Identify the state of matter where particles have the highest kinetic energy.
Solution:
The state.
Explanation:
Particles in a gas move at high speeds () in random directions, meaning they possess the most kinetic energy () compared to particles in solids or liquids at the same temperature.