Thermochemistry full notes

Energy

Different types

-Potential energy Potential energy is the stored energy of an object based on its position or condition. It has the potential to be converted into kinetic energy when the object's position changes.

- Kinetic energy is the energy that an object possesses as a result of its motion. It is quantitatively defined by the formula:

Law of conservation Energy

Conduction : transfer of heat by directed contact between objects

Convection : transfer of heat by bulk movement of mater in liquids or gasses

radiation : transfer of heat by electromagnetic waves

Specific heat: amount of energy required to raise the temp of 1g of a substance by 1 degree Celsius or 1 kelvin

• each pure substance has its own unique value

insulator ( above 1)

• transfers heat and energy poorly

Conductor ( Below 1)

• transfers heat and energy easily

• low specific heat value

chemical potential energy

• energy stored in chemical bond of a substance

• energy is absorbed when bonds are broken

Enthalpy : amount of lost or gained gained during a chemical or physical reaction

Endothermic

-process in which energy is absorbed

-energy is negative

Sublimation is an endothermic process where a substance transitions directly from a solid to a gas, absorbing heat energy in the process.

Deposition is the process in which a substance transitions directly from a gas to a solid state without going through a liquid phase. This phase change often occurs when vapor molecules lose energy and form a solid, typically seen in processes like frost formation on surfaces.

Hess law

Hess's Law states that the total enthalpy change during a chemical reaction is the same, regardless of whether the reaction occurs in one step or multiple steps. It implies that the enthalpy change is a state function and only depends on the initial and final states of a system, not the path taken to get there.

Exothermic reactions are processes in which energy is released into the surroundings, usually in the form of heat. During these reactions, the total enthalpy change is negative, indicating that the energy of the products is lower than that of the reactants.

Convection : is the transfer of heat by the bulk movement of matter in liquids or gases. This process involves the movement of warmer, less dense fluid rising while cooler, denser fluid sinks, creating a circulation pattern that distributes heat throughout the substance.

Exothermic process : energy of products is less than energy of reactants

Endothermic process: products have more energy than reactants

Entropy is the measure of molecular randomness or disorderedness of a system

Entropy levels : Gasses, liquids, ( solutions ig) and then solids

Gibbs Free energy : Measures how favorable a process is based on thermodynamic conditions

Thermodynamically Favored : reactions occurs without external interventions

Thermodynamically unfavored : process does not occur under the current conditions

Favorability : reactions are more favored when they are exothermic, entropy increases, and gibbs free energy is negative