Science 3rd Quarterly Exam

Main Idea: Gases exhibit a unique set of properties explained by the kinetic molecular theory, which outlines the relationships between amount, volume, temperature, and pressure.

No definite shape and volume: Gases fill any container and assume its shape and volume.
Diffusion: Gases spread out evenly when mixed in a container.
Highly compressible: Gases can be significantly compressed.
Lower densities: Gases have lower densities compared to liquids and solids.

Tiny particles: Gases consist of tiny particles with large distances between them, making their volume negligible compared to the container's.
Insignificant attractive forces: Attractive forces between gas particles are negligible, allowing them to fill available space freely.
Constant motion: Gas particles are in perpetual motion, changing direction upon collision; these collisions are perfectly elastic.
Kinetic energy: Average kinetic energy of gas particles is uniform for all gases at a given temperature, directly proportional to the Kelvin temperature.

Temperature: Represents the average kinetic energy of gas particles.
Volume: The space occupied by gas particles.
Pressure: The amount of force applied per unit area; can be measured using a barometer.

Gas Laws: Principles that predict gas behavior under varying conditions of pressure, volume, and temperature.

Statement: Pressure is inversely proportional to volume when temperature is constant.
Example: When a syringe's plunger is pushed, volume decreases, leading to increased pressure.

Statement: Volume is directly proportional to temperature (in Kelvin) when pressure is constant.
Example: Heating air in a balloon causes it to expand and increase in volume.

Statement: Pressure is directly proportional to temperature (in Kelvin) when volume is constant.
Example: As a car tire heats up, the pressure increases due to rising temperature.

Statement: Volume is directly proportional to the number of moles of gas when pressure and temperature are constant.
Example: Adding more air to a balloon increases its volume if temperature and pressure remain unchanged.

Statement: Combines other gas laws into one equation, illustrating pressure, volume, temperature, and amount of gas relationships.
Example: The air inside a basketball behaves according to the ideal gas law.

Main Idea: Chemical reactions rearrange atoms to form new substances, expressed in balanced equations.

Color Change: New products exhibit different colors (e.g., rust formation).
Temperature Change: Reactions can exhibit heat release or absorption.
Emission of Light: Some reactions produce light through energy release of electrons.
Evolution of Gas: Bubbles indicate gas production during reactions.
Precipitation: Formation of an insoluble solid substance in a liquid medium.

Structure: Represent reactants on the left and products on the right, with the physical state indicated in italics within parentheses.

Combination: Two or more reactants form a complex substance.
- Example: $A + B → AB$
Decomposition: A compound breaks down into simpler constituents.
- Example: $AB → A + B$
Single Replacement: A more active element replaces a less active one in a compound.
- Example: $AB + X → AX + B$
Double Replacement: Two compounds exchange ions to form new compounds.
- Example: $AX + BY → AY + BX$