Heating and Cooling Curves, Changes of State, and Specific Latent Heat

Comprehensive vocabulary flashcards covering heating and cooling curves, changes of state, particle arrangements, and specific latent heat calculations.

Specific Latent Heat

The measure of energy needed to melt or boil $1\,\text{kg}$ of a substance, which changes the state of matter without changing its temperature.

Specific Latent Heat Equation

The mathematical relationship expressed as $E = m \times L$, where $E$ is energy transferred in joules ($\text{J}$), $m$ is mass in kilograms ($\text{kg}$), and $L$ is specific latent heat in joules per kilogram ($\text{J/kg}$).

Specific Latent Heat of Water

A physical constant with a value of $334\,\text{kJ/kg}$ for melting and $2260\,\text{kJ/kg}$ for boiling.

Specific Latent Heat of Lead

A physical constant with a value of $23\,\text{kJ/kg}$ for melting and $871\,\text{kJ/kg}$ for boiling.

Specific Latent Heat of Oxygen

A physical constant with a value of $13.9\,\text{kJ/kg}$ for melting and $213\,\text{kJ/kg}$ for boiling.

Heating Curve Plateau

A horizontal, flat section on a heating curve where a change of state occurs and energy is absorbed to overcome attractive forces between particles, while average kinetic energy and temperature remain constant.

Sloping Sections of a Heating Curve

The rising portions of a curve where heat input increases both the temperature and the average kinetic energy of the particles within a single state of matter.

Four-Mark Explanation of Melting

A structured explanation describing that: 1. Energy transfers to the ice; 2. Energy overcomes attractive forces; 3. Average kinetic energy stays constant; and 4. Temperature stays constant.

Freezing (Cooling Curve Plateau)

A phase change where liquid becomes solid, releasing energy as attractive forces form between particles, while average kinetic energy and temperature stay constant.

Condensation

A cooling transition from gas to liquid that releases extra latent energy before the liquid itself begins to cool down.

Sweating (Cooling Mechanism)

A cooling process where higher-energy water particles evaporate from the body, transferring thermal energy away from the skin.

Hot-Day Laundry Evaporation

The observation that wet laundry dries faster at higher temperatures because water particles have higher kinetic energy and therefore evaporate faster.

State Coexistence Sections (B–C and D–E)

Intermediate segments of a heating curve where two phases coexist simultaneously (solid and liquid at B–C, or liquid and gas at D–E) because a change of state is in progress.

Particle Model: Solid (Section A–B)

The state of matter in which particles are held in fixed positions within a lattice and vibrate in place, vibrating more rapidly as temperature rises.

Particle Model: Liquid (Section C–D)

The state of matter where particles are close together, able to move past each other, and move progressively more rapidly as heating continues.

Particle Model: Gas (Section E–F)

The state of matter where particles have the greatest freedom of motion, are spaced furthest apart, and move randomly in all directions.

Conservation of Particle Size

The principle stating that particles stay the same size during heating and cooling; only their movement and arrangement change.

Electrical Heater Method for Latent Heat

A four-step experimental procedure: 1. Heat ice with an electrical heater for several minutes; 2. Calculate $\text{Energy input} = \text{heater power} \times \text{heating time}$; 3. Measure the mass of water melted; 4. Determine $\text{Specific latent heat} = \frac{\text{energy input}}{\text{mass melted}}$.

Bubbles in Boiling Water

Gaseous pockets that form within boiling liquid water containing pure water vapour, rather than air.

Attractive Forces in Gases

Intermolecular attractions that exist between gas particles, though they are usually negligible in magnitude.

Brownian Motion

The observed phenomenon demonstrating that fluid molecules move continuously and collide with suspended particles.

Gas Pressure at Fixed Volume

The outward force generated when heating a fixed-volume gas, caused by faster-moving particles hitting the container walls more often and with greater force.

Heating vs. Cooling Graph Profiles

The graphical paths showing that heating ice produces a rise-flat-rise temperature profile, whereas cooling steam produces a fall-flat-fall temperature profile.