MindMap Gallery Thermochemistry
Mind map about thermochemistry, thermodynamic energy U (state function): the sum of the energies of all microscopic particles inside the system, the mathematical expression of the first law of thermodynamics: △U=Q W or △U system △U environment=0
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This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
Thermochemistry
basic concept
system
Open system: There is both material and energy exchange between the system and the environment.
Closed system: no exchange of matter, but there is exchange of energy
Isolated system: neither matter nor energy exchange
Environment: the part closely related to the system
Phase: a homogeneous part of a system with identical physical and chemical properties
State function: a physical quantity that describes the properties of a system
Features
When the state is certain, the state function is certain; when the state changes, the state function changes
Its change value is only related to the initial state and final state, and has nothing to do with the change path.
Classification by nature
Extensive properties: additive (volume, mass, etc.)
Strength properties: not additive (temperature, density, etc.)
stoichiometry
The reactants are negative, the products are positive, and the sum of the stoichiometric numbers is 0
For the same reaction, the stoichiometric numbers are related to the way the chemical equation is written.
Reaction progress (unit: mol)
Definition: ▲n of a substance in the reaction/stoichiometric number and chemistry of the substance It is related to the way the reaction equation is written, and the specific chemical reaction equation must be specified.
Molar reaction: a reaction with a reaction progress of 1 mol
First law of thermodynamics
Thermodynamic energy U (state function): the sum of the energies of all microscopic particles inside the system
Hot Q (not a state function)
Definition: The energy transferred due to the temperature difference between the system and the environment
The system absorbs heat from the environment, Q>0
The system releases heat from the environment, Q<0
Work W (not a state function)
Definition: A general term for other forms of energy transfer between the system and the environment except heat.
The environment does work on the system, W>0
The system does work on the environment, W<0
Classification of work
Volume work: The work done due to the volume change caused by the system's resistance to external pressure W=-P△V
Non-volume work: All forms of work except volume work
Mathematical expression of the first law of thermodynamics: △U=Q W or △U system △U environment=0
Heat and enthalpy of reaction
Isovolumetric reaction heat Qv (state function)
Definition: Under isothermal conditions, in a closed system, at constant volume and no non-volume work is done. The heat exchanged between the system and the environment during
△U=Qv, that is, all the heat absorbed (released) by the system from the environment is used to increase (reduce) the thermodynamic energy of the system
Measuring Qv: bomb calorimeter
Constant pressure reaction heat Qp (state function)
Definition: Under isothermal conditions, in a closed system, at constant pressure and no non-volume work is done. The heat exchanged between the system and the environment during
Define enthalpy H=U Pv, unit J or KJ, which is a state function and has extensive properties
△H=Qp, that is, all the heat absorbed (released) by the system from the environment is used to increase (reduce) the enthalpy of the system
Endothermic reaction △H>0, exothermic reaction △H<0
The relationship between Qp and Qv: Qp (△H) = Qv P△V
Reaction without gas participation △H≈△U
For reactions involving gas, △H=△U △nRT, △n=n (product gas)-n (reactant gas)
standard molar enthalpy change of reaction
Definition: The molar enthalpy change of a chemical reaction in the standard state
Thermodynamic standard state: any temperature T, standard Pure gas/liquid under pressure 100Kpa
Standard molar enthalpy of formation
Definition: The enthalpy change of the reaction when a unit amount of pure substance is produced from a specified element (usually the most stable element of an element in the standard state) under the standard state.
The only way to write the reaction equation is
The standard mole of the specified element is generated as 0
Calculation method: The standard molar enthalpy change of the reaction is equal to the standard molar enthalpy of formation of each substance participating in the reaction at the same temperature × the sum of their stoichiometric numbers
Notice
When expressing the standard molar enthalpy of formation of a reaction, the reaction equation must be stated
It can be considered that the enthalpy change of the reaction basically does not change with the temperature T, that is, at any T Standard molar enthalpy of formation≈298.15K