Chemical Reactions Flashcards

Flashcards covering vocabulary relating to thermal energy, calorimetry, enthalpy, and chemical reactions.

Thermal Energy

Sum of the kinetic energy (KE) of all particles in a substance.

Heat

Amount of thermal energy transferred in or out of a system.

Temperature

Average kinetic energy of the particles in a substance.

Conduction

Heat transfer through direct contact (when molecules touch).

Convection

Heat transfer through the movement of matter (currents); only happens in fluids (gas or liquid).

Radiation

Heat transfer through electromagnetic waves; does not have to pass through matter.

Conductors

Materials where heat can easily be transferred through (metals, water).

Insulators

Materials that block energy flow & slow heat transfer (air, styrofoam).

Enthalpy

Heat energy absorbed or released by a system during a chemical or physical process.

Calorimetry

Process of measuring the heat energy released or absorbed in a system.

Fusion

Phase change between solid & liquid (melting/freezing).

Vaporization

Phase change between liquid & gas.

Triple Point

Specific temperature & pressure where all three states of a substance can coexist at equilibrium.

Specific Heat Capacity (c)

Energy required to raise the temperature of 1g of a substance by 1°C; differs for every compound and its every phase.

Exothermic Reaction

Releases heat into the surroundings; enthalpy change (△Hrxn) is negative (-).

Endothermic Reaction

Absorbs heat from the surroundings; enthalpy change (△Hrxn) is positive (+).

Activation Energy (Ea)

The minimum amount of energy required for reactant molecules to undergo a successful chemical reaction.

Collision Theory

A model explaining how chemical reactions occur at the molecular level, requiring collision, correct orientation, and sufficient KE.

Thermochemical Equations

A balanced chemical equation that includes the reaction’s enthalpy change (△H).