MindMap Gallery Chemistry-Thermodynamics 2 Mind Map
This is a mind map about chemical thermodynamics 2, including the first law of thermodynamics, melting and thermodynamics, entropy and the direction of chemical reactions, etc. I hope it will be helpful for you to learn chemistry!
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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.
chemical thermodynamics
First law of thermodynamics
Basic concepts of thermodynamics
System and environment
Open system: material exchange energy exchange
Closed system: only energy exchange
Isolated system: neither matter nor energy exchange
nature of system
Extensive properties (capacity properties): additive, such as volume, mass, heat capacity, etc.
Intensity function: no additivity, such as temperature, pressure, density, viscosity, etc.
state
Physical and chemical properties of the system
Reversible expansion: W=-nRTln (V end/V start)
The driving force is infinitesimally small
The process is infinitely slow
Minimal external disturbance
The time required is infinite, the system does the maximum external work, and it is impossible to achieve
Thermodynamic energy U (internal energy)
The sum of all energies of all particles in the system except the overall potential energy and kinetic energy is a state function and a breadth property.
Without complete understanding, its absolute value cannot be determined (the same is true for H)
Heat and work (neither are state functions)
Thermal Q: T environment > T system, the system heat absorption (energy is transferred from the environment to the system) is a positive value Otherwise it is a negative value
Work W: "Except for heat, it is work". The work done by the environment on the system is positive, otherwise it is negative.
enthalpy
Closed system, pressure: initial state = final state = environment, only volume work is done
First law of thermodynamics: ΔU=Q W
enthalpy
Isobaric heat and enthalpy: Qp=ΔU pΔV=ΔH, H=U+pV, state, wide state
Isovolumetric heat: ΔU=Qv
Qp=Qv(Δn)RT
Enthalpy and Thermodynamics
express
pɵ: pressure=1×10^5Pa
Gas is a gas under standard pressure, solid (liquid) is a pure solid (pure liquid) under standard pressure
The standard state of the solvent in an ideal dilute solution is a pure liquid under standard pressure. The solute volume molar concentration = 1mol/L or the mass molar concentration 1mol/kg.
The subscript "r" represents a general chemical reaction, and the superscript "ɵ" represents the standard state. ΔH also has the heat of fusion fus, the heat of solidification sol; the heat of vaporization vap, the heat of condensation coa; the heat of sublimation sub
"m" means that 1 mol of reaction has occurred, and the reaction progress is 1 mol.
Commonly used standard enthalpy change at 298.15K
"f" means "standard generation", not an absolute value, but a relative value relative to the reference state element that generates it.
thermochemical equation
The aggregation state and even crystal type of the substance should be indicated. (g),(l),(s),(aq),(cr),C(diamond)orC(graphite)
ΔrHɵ(298.15K), unit kJ/mol
stoichiometry
Reaction progress: ɛ=ΔnB/ʋB=nB(ɛ)-nB(0)/ʋB
Geis' law
Standard molar enthalpy of formation
The enthalpy change when 1 mol of a substance is generated from the most stable element is called the molar enthalpy of formation. The enthalpy of formation under the standard state is the standard molar enthalpy of formation (standard molar heat of formation) ΔrHmɵ=∑ΔfHmɵ(product)-∑Δ fHmɵ(reactant) Measurement coefficient
calculate:
ΔrHmɵ=∑[ΔfHmɵ(298.15K)] product-∑[ΔfHmɵ(298.15K)] reactant=∑ʋB ΔfHmɵ(B,298.15K)
Entropy and the direction of chemical reactions
spontaneous process
The direction is single. If you want to reverse it, you must use external force to do work on it.
Have the ability to do work. The ability to do work is the internal driving force of spontaneous processes.
There is a certain limit. In short, the spontaneous process always tends to the equilibrium state in one direction. This is the limit of the spontaneous process under this condition.
entropy
The degree of chaos refers to the degree of irregularity or disorder of the particles that make up the system. Entropy is a measure of the degree of disorder of the system, represented by the symbol S. It is a state function with extensive properties. The entropy of a certain amount of pure material is a function of temperature and pressure.
Influencing factors
Aggregation state of matter: g>l>s
Temperature and pressure: As the temperature increases, the entropy value increases; For gaseous substances, as the pressure increases, the entropy value decreases; for solid and liquid substances, the pressure has little effect on the entropy value.
Relative molecular mass and molecular structure: complex molecules > simple molecules
Entropy change and the direction of chemical reactions
The principle of entropy increase (an expression of the second law of thermodynamics): In an isolated system, spontaneous processes always proceed in the direction of increasing system disorder, that is, the direction of entropy increase.
Key: The system and environment should be viewed as a whole to view entropy change, and the total entropy change should be used as the criterion. ΔS total = ΔS system ΔS ring
ΔS total: >0 The process proceeds spontaneously <0 The process does not proceed spontaneously, and its reverse reaction can proceed spontaneously =0 The system is in equilibrium
The third law of thermodynamics states that at absolute zero, the entropy value of any perfect crystal of pure substance is zero, recorded as S0=0 Entropy change ΔS=S(T)-S0 Note (?): For ions in aqueous solution, the standard molar entropy of H aqueous solution with activity 1 is zero.
The specified entropy of 1 mol of a substance in the standard state is called standard molar entropy, symbol Smɵ (T), and the unit J/mol/K standard entropy is all positive (with exceptions for aqueous solutions) (?). The standard molar entropy of a stable element is not is zero
Calculation of entropy change
ΔrSmɵ=∑[Smɵ(298.15K)]product-∑[Smɵ(298.15K)]reactant Measuring coefficient Approximately, it is considered that it does not change with temperature
Gibbs free energy and the direction of chemical reactions
G=H-TS, Gibbs free energy (Gibbs function), state function, breadth properties
Under the conditions of a closed system with isotherm and pressure, and only does volume work: ΔG<0 spontaneous; >0 non-spontaneous; =0 equilibrium
If the system undergoes a reversible process under isothermal and isobaric conditions, ΔG = W non-volume
Isotherm equation: ΔG=ΔH-TΔS
Derivation: Under isobaric conditions, when only volume work is done, ΔH system = Qp = -Qp ring, ΔS ring = Qp ring / T = - ΔH system / T, ΔS total = ΔS system ΔS ring, That is to say, ΔS = ΔS system - ΔH system/T, and then the isothermal equation can be obtained
ΔrGmɵ; ΔfGmɵ: The Gibbs free energy when 1 mol of a substance is generated from the most stable element is called the standard Gibbs free energy of formation of the substance.
calculate
Under standard conditions: ΔrGmɵ=∑[ΔfGmɵ(298.15K)] product-∑[ΔfGmɵ(298.15K)] reactant
Gibbs-Helmholtz formula: ΔG(T)=ΔH(T)-TΔS(T) Commonly used units are ΔrGmɵ(T)=ΔrHmɵ(298.15K)-TΔrSmɵ(298.15K).
Under non-standard conditions, ΔrGm = ΔrGmɵ RTlnJ. This formula is called the isothermal equation of a chemical reaction. The expression of J is similar to concentration entropy (?). For solutions, we use universal concentration, and for gases, we use pressure. Regulations: standard concentration = 1mol/L, standard pressure = 100kPa
expand?
The role of thermodynamics in biological systems
standard state in biochemistry
It is specified as C(H )=10^-7mol/l, ΔrGmɵ’=ΔrGmɵ RTlnC(H )^x
The standard Gibbs function of reactions occurring in living organisms becomes >0 but occurs spontaneously
Not carried out under standard conditions, coupling reaction, one highly spontaneous reaction drives another reaction
Coupling reactions in organisms
The product of one reaction is one of the reactants of another reaction, which can affect the position of equilibrium and even make impossible reactions occur as mentioned above.
In a biochemical coupling reaction, an enzyme catalyst can cause two reactions that have no common substances to occur simultaneously.
Reversible reactions and chemical equilibrium
Reversible reaction: A two-way reaction such as the ammonia synthesis reaction that can proceed in one direction or the opposite direction. Reversibility is a universal characteristic of chemical reactions.
Chemical equilibrium: V positive = V negative, the concentration or partial pressure of the reactants and products in the system remains unchanged, and the equilibrium state is the maximum extent that a chemical reaction can proceed under certain conditions.
Equilibrium constant
Experimental equilibrium constant (referred to as equilibrium constant)
It is the equilibrium constant measured directly by experiment according to the law of chemical equilibrium.
Kc=[c]^e[D]^g/{[A]^a[B]^b} is similar to the partial pressure type
standard equilibrium constant
It has no unit, has one dimension, and is calculated by thermodynamic methods.
Kɵ=([C]/Cɵ)^e([D]/Cɵ)^g/{([A]/Cɵ)^a([B]/Cɵ)^b} The partial pressure formula is similar
Water in pure solid phase, liquid phase and dilute solution can be regarded as a constant and does not need to be written out.
multiple balances
Addition and subtraction between chemical equations is the multiplication and division between equilibrium constants. If a chemical equation is multiplied by the measurement coefficient, the equilibrium constant will be reduced to the original power.
The relationship between Kɵ and ΔrGmɵ
ΔrGm=ΔrGmɵ RTlnJ, the original formula is equal to 0 at equilibrium, and then through the relationship between J and K, lgKɵ=-ΔrGmɵ/2.303RT, ΔrGm=-RTln (Kɵ/J)
Applications of Standard Equilibrium Constants
Determine the limit of reaction progress, predict the direction of reaction, and calculate the composition of the equilibrium system
shifts in chemical equilibrium
The effect of concentration on equilibrium movement, that is, the change relationship can be deduced through the relationship between Kɵ and ΔrGmɵ
The effect of temperature on chemical equilibrium, lgK1ɵ/K2ɵ=ΔrGmɵ*(1/T1-1/T2)/2.303R. It can be seen that the greater the absolute value of the standard molar enthalpy change, the greater the impact of temperature on the equilibrium constant.
The influence of pressure on balance. If the volume of the system changes from V to V/x, then J=x^(e g)-(a b)Kɵ can be calculated, and then the relationship between equilibrium movement and Δn can be derived.