Heat

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Calorimeter Noun

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[kal-uh-rim-i-ter]

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Calorimeter

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An insulated device used for measuring the amount of heat absorbed or released during a chemical or physical process.

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Example: This diagram shows a simple calorimeter made of insulated styrofoam cups, a lid, a thermometer, and a stirrer, used to measure heat changes.

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Bomb Calorimeter Noun

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[bom kal-uh-rim-i-ter]

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Bomb Calorimeter

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A type of constant-volume calorimeter used to measure the heat of combustion of a particular reaction, like in foods.

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Example: This diagram shows a bomb calorimeter, a device used to measure the heat released from a reaction by observing the temperature change in surrounding water.

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Specific Heat Noun

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[spuh-sif-ik heet]

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Specific Heat

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The amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius.

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Example: This diagram shows that different materials, like water and copper, require different amounts of heat to change their temperature, which is called specific heat.

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Thermochemistry Noun

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[thur-moh-kem-uh-stree]

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Thermochemistry

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The study of heat changes that accompany chemical reactions and changes in physical state, such as melting or boiling.

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Example: This diagram shows combustion, a chemical reaction where fuel and oxygen produce heat, which is a key example of a process studied in thermochemistry.

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System Noun

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[sis-tuhm]

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System

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The specific part of the universe, such as a chemical reaction, that is being studied for its energy changes.

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Example: This diagram shows a 'system' as a defined area, separated from its 'surroundings' by a 'boundary,' a core concept for studying heat transfer.

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Surroundings Noun

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[suh-roun-dingz]

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Surroundings

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Everything in the universe that is external to the system being studied and can exchange energy with that system.

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Example: In science, the 'surroundings' are everything outside of a defined 'system'. This diagram shows heat moving between the system (beaker) and its surroundings (air and table).

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Exothermic Process Noun

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[ek-soh-thur-mik pros-es]

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Exothermic Process

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A chemical reaction or physical change that releases energy, typically as heat, from the system into its surroundings.

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Example: A chemical reaction in a test tube releases energy, shown by arrows pointing outwards, which heats up the surroundings.

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Endothermic Process Noun

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[en-doh-thur-mik pros-es]

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Endothermic Process

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A chemical reaction or physical change that absorbs energy, typically as heat, from its surroundings into the system.

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Example: This diagram shows an instant cold pack. When the inner bag of water is broken, it mixes with ammonium nitrate, causing a chemical reaction that absorbs heat.

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Enthalpy (H) Noun

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[en-thal-pee]

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Enthalpy (H)

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A thermodynamic property representing the total heat content of a system when it is held at a constant pressure.

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Example: This image shows that adding heat energy increases the enthalpy (total heat content) of water, causing it to change temperature and state, from solid ice to boiling liquid.

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Enthalpy of Reaction (ΔHrxn) Noun

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[en-thal-pee uv ree-ak-shun]

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Enthalpy of Reaction (ΔHrxn)

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The change in enthalpy during a chemical reaction, which represents the amount of heat absorbed or released by the system.

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Example: This graph shows that the enthalpy of reaction (ΔHrxn) is the change in heat energy from the start (reactants) to the end (products) of a chemical reaction.