Chemical Reactions, Energy, and Conservation of Energy

A set of vocabulary flashcards covering chemical reactions, combustion types, the triangle of fire, thermal energy, heat, and the conservation and efficiency of energy.

Chemical Reaction

A process that involves the creation of new substances from old substances via a rearrangement of particles of pure substances, producing changes in properties that are not reversible.

Signs of a Chemical Reaction

Indicators that a chemical change has occurred, including color changes, gas release, precipitate formed, light, electricity, and heat or cold produced.

Oxidation

Any reaction with oxygen, with examples including rust, fruit turning brown, and combustion.

Combustion

An oxidation reaction that releases lots of energy.

Triangle of Fire

A model used to describe the conditions necessary for combustion to occur: oxidizer ($O_2$), fuel, and ignition temperature.

Rapid Combustion

A type of combustion that releases lots of energy in a short amount of time, such as a campfire.

Slow Combustion

A type of combustion that releases small amounts of energy over long periods of time; another way of describing rust.

Spontaneous Combustion

Combustion that appears to occur without any outside source of ignition, such as forest fires occurring during a drought.

Energy

The ability to do work or to produce a change, measured in units of Joules ($J$) or kilojoules.

Law of Conservation of Energy

A fundamental principle stating that energy cannot be created or destroyed, only transferred or transformed from one form to another.

Thermal Energy

Energy possessed within an object or system due to the movement of the particles within that object or system.

Factors Affecting Thermal Energy

The two conditions influencing thermal energy: the number of particles (the mass or volume) and temperature (how fast the particles move).

Heat

The transfer of thermal energy between objects, which always flows from warmer objects to cooler objects.

Energy Efficiency ($E\%$)

A calculation of the proportion of energy successfully converted into useful work, given by the formula $\text{Energy Efficiency} = \frac{\text{Useful output energy}}{\text{Total input energy}} \times 100$.

Joule ($J$)

The standard unit used to measure energy and useful energy.