Kazunari Ninomiya x defective robot, a unique combination is born!Starring movie "TANG Tang" released in 2022
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If Mr. Ninomiya plays the main character, Ken, who will go on an adventure with a robot in the future world, I made an offer with such an expectation that a ridiculous chemical reaction would occur.
Warner Brothers Japan GK will star in Japan's leading actor, Kazunari Ninomiya, in the new movie "TAN ... → Continue reading
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Wikipedia related words
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Chemical reaction(Chemical reaction,English: chemical reaction) Refers to a chemical change or a process in which a chemical change occurs..Chemical changeAnd one or moreChemical substanceChanges into one or more different chemicals, Pre-react chemicalsatomBonding to each other, or conversely breaking the bond, or from the chemical moleculeElectronicAre emitted or, on the contrary, take in electrons. In a broad sensesolvent SoluteTomeltchangeOr atomicIsotopeChange to another isotope,liquid solidChange toMF2(P386)Etc. are also called chemical changes.
Before and after chemical changes,分子Although the bond of the atoms that make up a molecule may change to another molecule, the atom itselfAtomic numberIt does not change to an atom (however, there are changes in isotopes and exchange of electrons between atoms). At this point the atom itself changes to another atomNuclear reactionIs very different from.
In the chemical reaction, the chemical substance before the reactionReactant(reactant), chemical substance after reactionProduct(product), the process isChemical reaction formulaIt is written in. For example, a reactant(hydrochloric acid)When(Sodium hydroxide) Is a chemical reaction product(water molecule)When(Salt) Is a chemical reaction formula that shows the situation
In the case of a chemical reaction that creates a product from a reaction product, a chemical reaction that creates a reaction product from a product also occurs at the same time (such asWhen you want to emphasize that there is a reverse chemical reactionIs a chemical reaction arrow"not"". ).
Therefore, the reaction rate of the chemical reaction that creates a product from the reaction product is opposite to that of the chemical reaction. It will be balanced in the state. This stateChemical equilibriumThat is. (In addition, the phenomenon that the product finally disappears as a result of the chemical reaction is that the product is in a chemical equilibrium with 0).
Changes in chemical reactions
Trends that consider interactions with the outside world
Chemically changing system (Reaction system) Is generally externalInteractionWhile undergoing chemical changes (for example,Heat of reactionRadiate heat to the outside). Under these circumstances, the following facts are known:
- Chemical changes常 に, SystemEntropySsysAnd the entropy of the outside worldSsurrTotal entropyStotalVoluntarily progresses toward increasingMF2(P393)
さ ら に,
- The spontaneous reaction is常 に, Change the reaction mixture towards equilibriumMF2(P385).
Therefore, if the reaction system is isolated from the outside,Equilibrium constantKcAnd at the current timeReaction indexQcYou can know in which direction the reaction goes by comparing withMF2(P385).
Change trend of reaction system
Two states of reaction systemA,BAgainstAAnd the entropy of the system atBThe difference in the entropy of the system whenΔSsysThen,
- ΔSsys>0When, the system is in the stateBからAChange toMF2(P393)
- ΔSsys<0When, the system is in the stateAからBChange toMF2(P393)
If the entropy of the system does not change with time, the system is in equilibrium.MF2(P393).
As a general tendency, the internal energy of the system and theEnthalpyDecreases butMF2(P393), Not always. For example氷In waterDissolutionWhen it does, the system voluntarily absorbs heat from the outside.MF2(P386), The internal energy and enthalpy of the system increaseMF2(P386).
The decreasing tendency of internal energy and enthalpy is due to these values satisfying entropy and a relatively simple relational expression. Detail isThermodynamic potentialPlease refer to the item.
Free energy expression
As described above, the tendency of system change can be described by entropy, but entropy is not a physical quantity that can be directly measured, so in chemistryGibbs Free EnergyIs often used to describe the change tendency of the system.MF2(P386).. This section describes this description method. In this section, the Gibbs free energy and enthalpyThermodynamic potentialAssuming basic knowledge of.
First, we impose the following two assumptions on the reaction system:
- The temperature of the reaction system is always constant
- Reaction system temperature and outside temperature are always equal
The first assumption is satisfied if all the heat generated in the reaction system due to the chemical change can be released to the outside of the system. The second assumption is satisfied if the outside is sufficiently wide and is almost unaffected by the heat released from the reaction system. Below, the temperature of the reaction system = outside temperatureTWrite.
Gibbs free energy of a given systemGAnd enthalpyHIs the entropy of the systemS,temperatureTBy
Since the following relational expression is satisfied, based on the above assumption,
And the total internal energy outside the reaction systemUtotal,pressurePtotal,volumeVtotal The
However, the first term is 0 due to the law of conservation of energy, and the second term is also the pressure change for the whole.dPtotalCan be considered nonexistent, so in the end
- Outside the reaction systemChemical potentialAnd pressure changes, etc.Strong variable(For examplepolarization,MagnetizationCan be ignored
Therefore, based on the above assumptions, the increase in the total entropy causes a decrease in the Gibbs free energy of the reaction system. So the following conclusions can be drawn:
- ΔGsys<0When, the system is in the stateBからAChange toMF2(P395)
- ΔGsys>0When, the system is in the stateAからBChange toMF2(P395)
If the Gibbs free energy of the reaction system does not change with time, the system is in an equilibrium state.MF2(P395).
Type of chemical reaction
Chemical reactionElectronicThe bond is cleaved and generated with the movement of. When classifying chemical reactions by focusing on chemical bonds and electron transfer methods,Ion reaction (ionic reaction),Radical reaction (free-radical reaction),Pericyclic reaction (pericyclic reaction). is thereChemical speciesConsidering the reaction that makes a bond with another chemical species, the ionic reaction is a chemical reaction in which an electron pair is donated from one chemical species to generate a new bonding orbital, such as electron withdrawing property and electron donating property. The bias of the charge between the atoms governs the direction of the reaction. The radical reaction is a chemical reaction in which one electron is donated from each of the chemical species to form a new bonding orbital. The pericyclic reaction is a chemical speciesπ orbitからs orbitIs a chemical reaction in which new bonds are formed at two or more places by conversion through a cyclic transition state. The cleavage is the reverse reaction of the bond.
When considering a chemical reaction based on the reaction mechanism and the difference in the composition of reactants and products,Substitution reaction,Addition reaction,Elimination reaction,Rearrangement reactionEtc.
Hydrolysis,Dehydration reaction,Addition polymerization,Condensation polymerization(Polycondensation),Oxidation reaction,Reduction reaction,neutralizeReactions are classified according to the purpose of the chemical reaction and consist of one or more of the above four reaction mechanisms.
Chemical reaction theory
The theory that explains chemical reactions is based on empirical rules derived from the accumulation of chemical reaction cases andphysicsExplainPhysical chemistryProgress will be made as the theory is constructed. Therefore,physicsIn line with the development of the chemical reaction theory, the chemical reaction theory developed through stages.
18st centuryから19st centuryToelement Antoine Lavoisier,John DaltonAt the same time that they were discovered, a law has been found regarding the weight ratio of the chemically reacting reactant and product. The theory regarding the quantitative relationship of the components involved in these chemical reactions isStoichiometryIs organized as. Stoichiometry is generally a rule of thumbLaw of proportionality,Law of multiple proportionalityKnown as.
19st centuryIn the second halfQuantitative analysisThe law is established20st centuryWhen it becomes possible to measure the amount of change in chemical substances by developing over time,Chemical equilibriumAnd the speed at which the reaction progresses,Reaction rate formulaIs formulated asSubstance amount,MolarityAndtemperatureHas a strong influence on the amount of chemical reaction components and its change.thermodynamicsMakes it possible to physically explain the behavior common to molecules (or) atoms, such as chemical equilibrium andReaction rateThe physicochemical theory of was established. The determinants of the amount of components in a chemical reaction and the speed of change areChemical potentialIn a broad sense of thermodynamicsReaction kineticsSystematized by. The chemical potential isSecond law of thermodynamicsIs a physicochemically interpreted index that determines the direction of reaction (or equilibrium).Reaction kineticsThe reaction rateSubstance amount,temperatureCan be explained as a microscopic behavior such as a molecule.
Reaction kinetics, especiallyTransition state theoryChemical reaction by thermodynamics andStatistical mechanicsIt has become possible to rationalize it as the action of molecules of reactants, rather than the theory of populations such as. Today we associate molecular structure with chemical reaction for each type of reactionReaction mechanismChemical reactions are studied by building a model.
As a basic principle for constructing a reaction mechanism model, as the transfer of valence electrons or covalent bonds to which electrons belongChemical bondAs a semi-empirical principleOrganic electron theoryWas systematized. Organic electron theoryHSAB ruleEmpirically assumed inElectron pairThe behavior ofQuantum chemistry OfMolecular orbital methodIt is possible to formulate with. Also,Pericyclic reactionEtc someStereospecificSuch a reaction mechanism cannot be explained by the classical electron behavior,Molecular orbitalDeals with the principle of associativityFrontier orbital theoryExplains the reaction mechanism.
The reaction mechanism constructed as above isMolecular dynamicsThe validity of the model and the behavior of the reaction are verified by the method ofComputerWith the rapid expansion of computing performance ofComputational chemistryDue to the development of technological methods, computersimulationIt is also possible to predict the chemical reaction with.
Factors that affect chemical reactions
When actually performing a reaction or developing a reaction system, the speed and success or failure are not a little affected by the influence of various factors and conditions surrounding the reaction. This section outlines the factors and conditions that should be considered for the effects of chemical reactions, from a qualitative and empirical perspective. Since the reaction mechanism varies depending on the reaction, there are of course some cases that do not apply to the following discussion. For reactions that are known in detail,Reaction rate formulaIt should be considered more quantitatively, taking into consideration such factors.
- temperature -Many reactions increase in velocity at higher temperatures because more energy is given to the system. In general, the standard is that if the reaction temperature rises by 10 °C, the reaction rate will double. However, the reaction may fail as a result of raising the temperature, such as inducing side reactions, decomposing intermediates, or causing runaway reaction.
- concentration -In the case of multi-order reactions, the higher the concentration of the reaction mixture, the higher the frequency of collisions between the reactants, the higher the probability that the reaction will occur, and the higher the speed. It becomes remarkable in the case of chain reaction. In the case of macrocycle synthesis, in order to give preference to intramolecular reaction over intermolecular reaction, it is often carried out under conditions of high dilution. In addition, in the 0th and 1st order reactions, the effect of concentration only affects the temperature change of the system. Also when adjusting the concentration, it is necessary to consider the same problems as when adjusting the temperature, such as side reactions and runaway.
- pressure -Normally, reactions involving gas become faster with increasing pressure. In the case of gas, an increase in pressure is virtually equivalent to an increase in concentration, so the same argument as for concentration holds. When the number of moles is different between the primordial system and the production system, the pressure affects the ratio of each compound when the equilibrium state is reached.
- Light -Light is a form of energy. It may also affect the reaction pathway. Some reactions must be protected from light to prevent side reactions. Positively use lightLight reactionThen, it is necessary to consider the wavelength and intensity of the light used.
- catalyst -When a catalyst is added to the reaction, it becomes possible to take a reaction path with lower activation energy, and both the forward and reverse reaction speeds increase. Unlike the equivalence reaction, the catalytic reaction smoothly rotates the catalytic cycle, so that it is necessary to consider activation and stabilization of the catalyst.
- Surface area - Heterogeneous catalystIn the surface reaction using, for example, the reaction rate increases as the surface area increases. The higher the surface area to volume ratio, the more sites the reaction takes place and the faster the reaction takes place. Similarly, in solid-liquid, gas-liquid multi-phase systems, water-oil layers, and other multi-layer systems, the reaction takes place at or near the point where different phases/layers contact, so surface area and agitation are important. Become.
According to Digital Daijisen, "the combination of multiple things to produce an unexpected effect" can be likened to a chemical reaction.
- physical - Condensed matter physics
- List of chemical reactions
- State change
- Chemical equilibrium
- Personal name reaction
- [MF1] J. McMurry, RC Fay “McMurry General Chemistry (XNUMX)” Translated by Hiroshi Ogino, Manabu Yamamoto, Koichi Ohno,Tokyo Kagaku Doujin, August 2010, 11.ISBN 9784807907427.
- [MF2] J. McMurry, RC Fay "McMurry General Chemistry (XNUMX)" Translated by Hiroshi Ogino, Manabu Yamamoto, Koichi Ohno,Tokyo Kagaku Doujin, August 2011, 2.ISBN 9784807907434.