Motion and States of Matter: Gases and Liquids

Gases are in constant, random, rapid motion.
Individual gas particles are considered to have no attractive forces between them.
When gas particles collide, they do not stick together; they bounce off each other (elastic collisions).
Temperature of a gas depends on the energy of its particles.

Kinetic Energy (K): K = \frac{1}{2} m v^2 where:
- K is kinetic energy.
- m is the mass of the gas particle.
- v is the velocity of the gas particle (not volume).
Total Energy of a Gas (E): E = \frac{3}{2} n R T where:
- E is the total energy of the gas.
- n is the number of moles of gas molecules (a concept related to chemistry, often using values like 0.0821 or 8.314).
- R is the ideal gas constant.
- T is the temperature in Kelvin (e.g., 300 \text{ K}).

Expansion: Gases readily diffuse throughout an entire room because they are in constant, random, rapid motion. They tend to maximize the distance between their particles, leading to even distribution over time.
- Example: If perfume is sprayed, it will eventually spread evenly throughout a room, not remain concentrated.
Fluidity: Gases are considered fluids because their particles move freely throughout the room, allowing them to flow and take the shape of their container.
Density: Gases have a very low density compared to solids and liquids.
Compressibility: Gases are highly compressible. A large amount of gas can be forced into a small area (e.g., scuba tanks, propane tanks).

Property	Gas	Liquid	Solid
Fluidity	Most fluid	Fluid	Least fluid (rigid)
Compressibility	Most compressible	Slightly compressible (small amounts)	Least compressible

Diffusion: The spontaneous mixing of particles of two substances caused by their random motion, resulting in even spreading.
- Example: Perfume spreading throughout a room; two intermingling gases when a barrier is removed.
Effusion: The escape of gas particles through tiny holes in a container.
- Example: A balloon slowly deflating over time as gas molecules escape through microscopic pores in the rubber.

Ideal Gas: A hypothetical gas that perfectly adheres to the assumptions of the kinetic-molecular theory (e.g., no intermolecular forces, particles have negligible volume).
Real Gas: A gas that does not behave ideally, deviating from ideal gas assumptions.
Gases behave more like real gases (deviate from ideality) under conditions of low temperature and high pressure.
Gases behave more like ideal gases under conditions of high temperature and low pressure.
Real-world implications: In diving, high pressure and lower temperatures cause gases to dissolve into the blood (e.g., nitrogen narcosis, decompression sickness), which is problematic because gases deviate from ideal behavior under these conditions.

Constant Motion: Liquid particles are in constant motion, though slower and more restricted than gas particles.
Fluidity: Liquids are fluids because their particles can slide past each other, allowing them to flow and take the shape of their container.
Density: Liquids have high densities compared to gases.
- There are different densities among liquids (e.g., denser liquids settle below less dense liquids).
- Liquids are generally less dense than solids, with water being a notable exception where solid ice is less dense than liquid water, causing ice to float.
Compressibility: Liquids are very slightly compressible, but not nearly as much as gases, and more so than solids.
- Application: This property is crucial in hydraulic systems, where the incompressibility of liquids transmits force effectively to move mechanical parts (e.g., hydraulic lifts).
Diffusion: Liquids can diffuse, but generally much slower than gases.
- Example: Food coloring spreading in water.
- Effect of Temperature on Diffusion: Higher temperatures lead to faster diffusion in liquids due to increased kinetic energy and more rapid particle motion.
  - Boiling water diffuses much faster than ice water because its particles have more kinetic energy.
  - K and E equations (K = \frac{1}{2} m v^2 and E = \frac{3}{2} n R T) explain the relationship between temperature and kinetic energy.

(Incomplete discussion in transcript, but introduced as a concept related to liquids).