Heat, Temperature and Calorimetry

Thermochemistry

The branch of chemistry focused on the study of heat changes that accompany chemical reactions and physical changes of state. It explores how energy is transferred and transformed in these processes.

Energy

The capacity to perform work or supply heat. Energy exists in various forms and can be converted from one form to another.

Heat (q)

A form of energy that flows between objects due to a temperature difference. Heat always moves from a warmer object to a cooler object until thermal equilibrium is reached.

Temperature

A measure of the average kinetic energy of the particles within a substance. It indicates the hotness or coldness of an object. Adding heat energy increases the kinetic energy of molecules, leading to a rise in temperature.

Kinetic Energy

The energy possessed by an object due to its motion. At the molecular level, this relates to the speed at which particles are moving.

Potential Energy

Stored energy that an object possesses due to its position or chemical composition. In chemistry, chemical potential energy is stored in the bonds between atoms.

Chemical Potential Energy

The energy stored within the chemical bonds of a substance. This energy depends on the types of atoms present and their arrangement within the molecule. During chemical reactions, this potential energy can be converted into heat or vice versa.

Exothermic Process

A process that releases heat energy into the surroundings. In these reactions, chemical potential energy is converted into heat, causing the surroundings to feel warmer.

Endothermic Process

A process that absorbs heat energy from the surroundings. In these reactions, heat energy is converted into chemical potential energy, causing the surroundings to feel cooler.

Law of Conservation of Energy

This fundamental law states that energy cannot be created or destroyed; it can only be converted from one form to another. In thermochemical processes, the total energy of the system and its surroundings remains constant.

Units of Energy

The standard unit of energy in the International System of Units (SI) is the Joule (J). Another common unit in chemistry is the calorie (cal), and the food calorie is denoted as Cal (note the capital C). The relationships between these units are: 1 cal = 4.18 J and 1 Cal = 1000 cal.

Calorimetry

The experimental technique used for the precise measurement of heat changes that occur during chemical and physical processes.

Calorimeter

A device specifically designed to measure the amount of heat absorbed or released in a chemical or physical change. Common examples include "coffee cup" calorimeters (constant pressure) and bomb calorimeters (constant volume).

Specific Heat (c)

The amount of heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius (or 1 Kelvin). It is an intensive property that depends on the composition of the substance. Common units for specific heat are J/g°C or cal/g°C.

Heat Transfer Equation (q=mcΔT)

This equation relates the heat transferred (q) to the mass of the substance (m), its specific heat (c), and the change in temperature (ΔT). It is a fundamental tool in calorimetry calculations.

Temperature Change (ΔT)

The difference between the final temperature (Tfinal) and the initial temperature (Tinitial) of a substance during a heat transfer process (ΔT = Tfinal - Tinitial).

Calorie (cal)

A unit of energy; the amount of heat required to raise the temperature of 1 gram of water by 1 degree Celsius. (Chemistry calorie)

Calorie (Cal)

A unit of energy, also known as a kilocalorie (kcal) or food calorie; equal to 1000 chemistry calories.

Calorimeter

An insulated device used to measure the heat absorbed or released during chemical or physical processes.

Calorimetry

The science of measuring heat changes in chemical and physical processes.

Chemical Potential Energy

The energy stored in the chemical bonds of a substance, determined by the types and arrangement of atoms.

Endothermic

A process that absorbs heat from its surroundings, resulting in a decrease in the temperature of the surroundings.

Energy

The ability to do work or supply heat.

Exothermic

A process that releases heat to its surroundings, resulting in an increase in the temperature of the surroundings.

Heat (q)

The transfer of thermal energy between objects or systems at different temperatures.

Joule (J)

The standard unit of energy in the International System of Units (SI).

Kinetic Energy

The energy of motion.

Law of Conservation of Energy

The principle that energy cannot be created or destroyed, only converted from one form to another.

Potential Energy

Stored energy that depends on the position, condition, or composition of an object.

Specific Heat (c)

The amount of heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius.

Temperature

A measure of the average kinetic energy of the particles in a substance; indicates the degree of hotness or coldness.

Thermochemistry

The branch of chemistry that studies the heat changes accompanying chemical reactions and physical changes of state.

Thermal Equilibrium

The state in which two objects in thermal contact have reached the same temperature and there is no net flow of heat between them.

ΔT (Delta T)

The change in temperature, calculated as the final temperature minus the initial temperature (Tfinal - Tinitial).