States of Matter Quiz

Study Notes

The physical state of a compound does not change its chemical structure; ice, liquid water, and steam are all H₂O.
Solids have definite volume and shape, with molecules that vibrate minimally due to low heat energy.
Adding heat to a solid increases molecular vibration, leading to a transition from solid to liquid, with liquids taking the shape of their containers.
A liquid has a definite volume but no fixed shape; as heat is added, it can transform into gas (vaporization).
Gases have neither definite shape nor volume, and the molecular structure remains unchanged during state changes.
Removing heat can revert a gas to liquid (condensation) or liquid to solid (freezing).

Most substances change state by altering molecular activity – e.g., liquid mercury freezes, solid lead melts.
For solids, increasing temperature allows molecules to move more freely, transitioning to a liquid state.
Further heating of a liquid allows molecules to overcome attractive forces, resulting in vaporization (boiling).
The reverse processes are condensation (gas to liquid) and freezing (liquid to solid).

Atoms in solids balance attractive and repulsive forces, resulting in a fixed position.
Solids maintain fixed shape and volume due to strong interatomic attractions; they expand slightly upon heating.
Particle arrangement in solids is neat and ordered, limiting their ability to flow.

Liquids differ from solids primarily in structure rather than atomic distance.
Isothermal processes describe constant temperature changes during states.
Charles's Law indicates gas volume varies directly with temperature at constant pressure.
Gay-Lussac’s Law connects absolute pressure and temperature of gas at constant volume.

For solids and liquids, specific heat capacity (s.h.c.) is energy needed to raise the temperature of 1 kg by 1 K.
Gases have different specific heat capacities:
- Cp (constant pressure) is higher than Cv (constant volume) due to additional work done during expansion.
Specific heat at constant pressure is crucial for processes like filling a hot air balloon.

Both piston and gas turbine engines require air compression before fuel ignition, significantly raising air temperature.
Piston Engine (Otto Cycle) steps: Intake → Compression (15:1) → Combustion → Exhaust.
Gas Turbine Engine (Brayton Cycle) steps: Intake → Compression → Combustion → Expansion → Exhaust.

In refrigeration, gas is compressed, heats up, then condenses into liquid, causing cooling as it evaporates inside the unit.
Air-conditioning systems can operate in reverse, utilizing refrigerant cycles to control temperatures.

Latent heat of fusion: heat required to melt a solid or extracted to freeze a liquid.
Latent heat of vaporization: heat needed to boil or vaporize a liquid, or extracted to condense a gas.

Thermal energy's movement involves conversion and transfer between different energy forms, following the law of conservation of energy.
Combustion generates heat, which can be helpful or undesirable, and is necessary for work, especially in gas turbines.

Visible light is electromagnetic radiation detectable by the human eye, with a speed of 3 x 10^8 m/s in a vacuum.
Visible light ranges between 400 and 700 nm, encompassing blue to red wavelengths.
The law of reflection states the angle of incidence equals the angle of reflection, measured against a normal line to the reflective surface.