Thermal Properties of Matter Flashcards

Flashcards covering key concepts related to thermal properties of matter, including internal energy, specific heat capacity, latent heat, and phase changes.

Internal Energy (U)

Energy store that is made up of total kinetic energy associated with the random motion of the particles and the total potential energy between the particles in the system.

Kinetic Energy of Particles

Energy possessed by particles due to their movement or vibration.

Potential Energy of Particles

Energy possessed by particles due to the forces of attraction between them.

Heat Capacity (C)

The change of a body's internal energy per unit change in its temperature.

Formula for Heat Capacity

Q = CΔθ

Specific Heat Capacity (c)

The change of a material's internal energy per unit mass for each unit change in its temperature.

Formula for Specific Heat Capacity

Q = mcΔθ

Implications of Water's High Specific Heat Capacity

Oceans act as an important heat sink, influencing global climate; circulating liquid in heating systems; cooling the skin through sweat.

Determination of Specific Heat Capacity of a Solid

Lagging, heater, thermometer, stopwatch; Q = mcΔθ; Pt = mcΔθ; IVt = mcΔθ

Determination of Specific Heat Capacity of a Liquid

Calorimeter, electronic balance, heater, thermometer, stopwatch; insulating lid, polished copper can, copper stirrer; Q = (mcΔθ)l + (mcΔθ)c; Pt = (mcΔθ)l + (mcΔθ)c

Melting

Change from solid to liquid state when energy is transferred without a change in temperature.

Solidification

Change from liquid to solid state.

Latent Heat of Fusion (Lf)

The amount of energy transferred to change a substance between the solid and liquid states at constant temperature.

Specific Latent Heat of Fusion (lf)

The amount of energy transferred per unit mass of a substance to change between the solid and liquid states at constant temperature.

Determination of Melting/Solidification Point of Naphthalene

Record temperature of naphthalene every minute until temperature falls to about 65°C, plot a graph of temperature against time, deduce solidification point from the graph.

Boiling

Change from liquid to gaseous state when energy is transferred without a change in temperature.

Condensation

Reverse of boiling; change from gaseous to liquid state.

Latent Heat of Vaporisation (Lv)

The amount of energy transferred to change a substance between the liquid and gaseous states, at constant temperature.

Specific Latent Heat of Vaporization (lv)

The amount of energy transferred per unit mass of a substance to change between the liquid and gaseous states, at constant temperature.

Molecular Explanation of Latent Heat

Latent heat of fusion is the energy required to weaken the intermolecular forces of attraction in a solid.

Working Principle of Refrigerator

Compressor compresses warm coolant vapor, vapor flows through external coil at high pressure, coolant transfers internal energy to surrounding air, coolant condenses into liquid, coolant enters the refrigerator.

Boiling Characteristics

Takes place at a particular temperature; throughout the liquid; produces bubbles; an external source of energy is needed.

Evaporation Characteristics

Takes place at any temperature; only at the surface of the liquid; no bubbles produced; energy is usually supplied by the surrounding medium.

Explanation of Evaporation (Kinetic Particle Model)

Molecules near the surface with higher KE escape into the air, lowering the liquid's temperature.

Factors Affecting Evaporation

Temperature, Area of exposed surface, Humidity of surrounding air, Motion of air, Atmospheric Pressure, Boiling Point of Liquid