| Term | Definition |
|---|---|
| chemical transformation | A process in which substances are converted into different substances through the breaking and forming of chemical bonds. |
| dissolution process | The process by which a solute dissolves in a solvent to form a solution, which can involve energy changes. |
| endothermic reaction | A chemical reaction that absorbs thermal energy from the surroundings, resulting in a positive enthalpy change. |
| exothermic reaction | A chemical reaction that releases thermal energy to the surroundings, resulting in a negative enthalpy change. |
| heat transfer | The process by which thermal energy is transferred between particles in thermal contact through collisions. |
| intermolecular interactions | Forces between molecules, such as hydrogen bonding, dipole-dipole forces, and London dispersion forces, that affect the physical and chemical properties of substances. |
| interparticle interactions | Forces between particles in a system that affect the energy changes during physical and chemical processes. |
| phase transition | The process by which a substance changes from one state of matter to another (solid, liquid, or gas). |
| physical transformation | A process in which the physical state or form of a substance changes without altering its chemical composition. |
| surroundings | Everything outside the system with which the system can exchange energy and matter. |
| system | The part of the universe being studied, which can exchange energy and matter with its surroundings. |
| temperature changes | Variations in the thermal energy of a substance that indicate energy changes in a system. |
| Term | Definition |
|---|---|
| chemical transformation | A process in which substances are converted into different substances through the breaking and forming of chemical bonds. |
| endothermic reaction | A chemical reaction that absorbs thermal energy from the surroundings, resulting in a positive enthalpy change. |
| energy diagram | A visual representation showing the energy changes that occur during a chemical or physical process, including initial and final energy states. |
| exothermic reaction | A chemical reaction that releases thermal energy to the surroundings, resulting in a negative enthalpy change. |
| physical transformation | A process in which the physical state or form of a substance changes without altering its chemical composition. |
| Term | Definition |
|---|---|
| heat transfer | The process by which thermal energy is transferred between particles in thermal contact through collisions. |
| kinetic energy | The energy possessed by particles due to their motion; greater in warmer bodies and lower in cooler bodies. |
| molecular collisions | Interactions between particles that can result in the transfer of energy between them. |
| temperature | A factor that influences reaction rate by affecting the kinetic energy and collision frequency of reactant molecules. |
| thermal energy | The total kinetic energy of particles in a substance due to their random motion. |
| thermal equilibrium | The state reached when two bodies in thermal contact have the same average kinetic energy and temperature, with no net transfer of thermal energy. |
| Term | Definition |
|---|---|
| calorimetry | An experimental technique used to measure the amount of heat transferred between systems. |
| dissolution | The process by which a solute dissolves in a solvent to form a solution, involving the breaking of bonds or interactions in the solute and formation of new interactions with the solvent. |
| endothermic reaction | A chemical reaction that absorbs thermal energy from the surroundings, resulting in a positive enthalpy change. |
| exothermic reaction | A chemical reaction that releases thermal energy to the surroundings, resulting in a negative enthalpy change. |
| first law of thermodynamics | The principle that energy is conserved in chemical and physical processes; energy cannot be created or destroyed, only transferred or transformed. |
| heat | Energy transferred between two systems due to a difference in temperature. |
| heat transfer equation | The mathematical relationship q = mcΔT used to calculate heat absorbed or released, where m is mass, c is specific heat capacity, and ΔT is the change in temperature. |
| molar heat capacity | The amount of thermal energy required to raise the temperature of one mole of a substance by one degree Celsius. |
| phase transition | The process by which a substance changes from one state of matter to another (solid, liquid, or gas). |
| specific heat capacity | The amount of thermal energy required to raise the temperature of one gram of a substance by one degree Celsius. |
| thermal energy | The total kinetic energy of particles in a substance due to their random motion. |
| Term | Definition |
|---|---|
| condensation | The process by which a gas converts to a liquid. |
| freezing | The phase transition process in which a liquid changes to a solid, releasing energy. |
| heat absorbed | The amount of thermal energy taken in by a system, typically during endothermic processes like melting or boiling. |
| heat released | The amount of thermal energy given off by a system, typically during exothermic processes like freezing or condensation. |
| melting | The phase transition process in which a solid changes to a liquid, requiring energy absorption. |
| molar enthalpy | The amount of heat energy absorbed or released per mole of substance during a process, typically measured in kJ/mol. |
| molar enthalpy of condensation | The amount of heat energy released when one mole of gas condenses to a liquid, equal to the negative of the molar enthalpy of vaporization. |
| molar enthalpy of fusion | The amount of heat energy required to melt one mole of a solid substance at its melting point, or released when one mole of liquid freezes. |
| molar enthalpy of vaporization | The amount of heat energy required to vaporize one mole of a liquid substance at its boiling point, or released when one mole of gas condenses. |
| phase transition | The process by which a substance changes from one state of matter to another (solid, liquid, or gas). |
| vaporization | The phase transition process in which a liquid changes to a gas, requiring energy absorption. |
| Term | Definition |
|---|---|
| bond breaking and forming | The process of breaking existing chemical bonds in reactants and forming new chemical bonds in products, which results in energy changes during a reaction. |
| chemical potential energy | The energy stored in the bonds of a substance that can be released or absorbed during a chemical reaction. |
| endothermic reaction | A chemical reaction that absorbs thermal energy from the surroundings, resulting in a positive enthalpy change. |
| enthalpy change | The difference in enthalpy between products and reactants in a chemical or physical process, representing the heat absorbed or released. |
| exothermic reaction | A chemical reaction that releases thermal energy to the surroundings, resulting in a negative enthalpy change. |
| heat (q) | The thermal energy transferred between a system and its surroundings, measured in joules or kilojoules. |
| kinetic energy of particles | The energy of motion of particles in a substance, which changes as chemical potential energy is released or absorbed, manifesting as a temperature change. |
| molar enthalpy of reaction | The enthalpy change per mole of a reactant or product in a chemical reaction, indicating the heat absorbed or released per mole at constant pressure. |
| thermal equilibrium | The state reached when two bodies in thermal contact have the same average kinetic energy and temperature, with no net transfer of thermal energy. |
| Term | Definition |
|---|---|
| bond energy | The average energy required to break a chemical bond between two atoms. |
| bonds broken | The breaking of chemical bonds in reactant molecules, which requires energy input to the system. |
| bonds formed | The formation of new chemical bonds in product molecules, which releases energy from the system. |
| endothermic reaction | A chemical reaction that absorbs thermal energy from the surroundings, resulting in a positive enthalpy change. |
| enthalpy change | The difference in enthalpy between products and reactants in a chemical or physical process, representing the heat absorbed or released. |
| exothermic reaction | A chemical reaction that releases thermal energy to the surroundings, resulting in a negative enthalpy change. |
| potential energy | The stored energy in chemical bonds and molecular structures that can be released or absorbed during a reaction. |
| Term | Definition |
|---|---|
| chemical process | A transformation in which substances are converted into different substances through the breaking and forming of chemical bonds. |
| enthalpy change | The difference in enthalpy between products and reactants in a chemical or physical process, representing the heat absorbed or released. |
| physical process | A change in the state or properties of matter that does not alter the identity of the substances involved. |
| product | Substances formed as a result of a chemical reaction. |
| reactant | Substances that are consumed in a chemical reaction to form products. |
| standard enthalpies of formation | The enthalpy change when one mole of a compound is formed from its elements in their standard states. |
| Term | Definition |
|---|---|
| chemical process | A transformation in which substances are converted into different substances through the breaking and forming of chemical bonds. |
| energy change | The difference in energy between the initial and final states of a system during a process or reaction step. |
| enthalpy | The total heat content of a system; at constant pressure, the enthalpy change equals the thermal energy transferred to or from the surroundings during a chemical or physical process. |
| enthalpy change | The difference in enthalpy between products and reactants in a chemical or physical process, representing the heat absorbed or released. |
| first law of thermodynamics | The principle that energy is conserved in chemical and physical processes; energy cannot be created or destroyed, only transferred or transformed. |
| Hess's law | The principle that the enthalpy change of an overall reaction equals the sum of the enthalpy changes of the individual steps in the reaction sequence. |
| physical process | A change in the state or properties of matter that does not alter the identity of the substances involved. |
| potential energy | The stored energy in chemical bonds and molecular structures that can be released or absorbed during a reaction. |
| thermal energy transfer | The movement of heat energy to or from the surroundings during a chemical or physical process. |