Aqua regia, also known as royal acid and nitrohydrochloric acid, is a highly corrosive liquid emitting yellow mistConcentrated hydrochloric acid(HCl) andConcentrated nitric acid(HNO ≮) A mixture of 3:1 by volume.It is one of the few liquids that can dissolve gold. Its name comes from its strong corrosiveness.
Aqua regia is composed of 1 unit volumeConcentrated nitric acidAnd 3 per unit volumeConcentrated hydrochloric acidMixedMixed acidSolute HCl and HNO usedthreeOfAmount of substanceThe ratio is 3:1).The content of hydrochloric acid is 22.8~25.8%, and the content of nitric acid is 2.5~3.1%.Aqua regia has strong oxidation capacity and was once mistaken as the king of acids (actually aqua regiaOnly corrosive, while the acid ratioconcentrated sulfuric acidTo be weak) (untilSuperacidI found that this was not the case).Some metals insoluble in nitric acid, such asgold、platinumCan be dissolved by aqua regia (platinum must be heated to react slowly, and platinum reaction is very slow, which is difficult to observe with the naked eye).But soluble in nitric acidSilver insteadSmaller solubility in aqua regia(because theInsolubleOfSilver chlorideFilm, while silver chloride andChloride ionComplex formation of Ag (Cltwo)twoIs limited).
Aqua regia also contains nitric acidOxidizabilityandChloride ionStrong coordination ability, so it can dissolvegold, platinum and other inactive metals.The addition of concentrated hydrochloric acid does not enhance the oxidation of nitric acid, but enhances the metalRestorability。Au and HClHydrogen chlorideCoordination forming HAuClfourTetrachloro alloyed acidIt enhances the reduction ability of metals and makes it possible to oxidize gold with nitric acid.
Proportioning conditions
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Both acids are strong.One of them is an acid with strong compatibility, which ensures a large amount of Cl-（Cl-With certain complexation), F-Although it shows stronger metal compatibilityHFIt is difficult to completely ionize in water, and it is difficult to guarantee a large amount of F-The exists of.Br-It is too easy to be oxidized to ensure the strength of the whole solutionOxidizability。So we must usehydrochloric acid。The oxidizability of an acid must be moderate, strong enough, but not too strong.Too strong, put Cl-The second condition is lost when a large amount of oxidation occurs, andConcentrated nitric acidIt is just the common acid that meets this condition.The two most common acid combinations can be said to be a perfect match.
howevernitric acidIn fact, it can be usedSelenic acid（HtwoSeOfour）AndTelluric acid（HsixTeOsix）Substitution is not common, but it has the same effect as nitric acid.The benefits areReduction product（HtwoEOthreeOr EOtwo(E=Se, Te) is not a gas and will not cause gas poisoning. All reaction products are in solution.
It was thought that aqua regia dissolved metals because of reaction: HNOthree+3HCl=NOCl+Cltwo+2HtwoO，It was produced in aqua regiachlorineAnd strongly oxidizingNitrosyl chlorideBecause of.Later, it was found that the more important reason was the high concentrationChloride ionrather thanmetal ionCan form stableComplex ionSo that the metalelectrode potential It is beneficial to the reaction in the direction of metal dissolution.
Take gold as an example: Au and Cl-Coordination formation [AuClfour]-Ions
It can be seen that: ① when there is no chlorine ion, nitric acid and chlorine are not easyGold oxide。②In the presence of chloride ion, its electrode potential decreases a lot.
In other words: due to the formation of [AuClfour]-ComplexThe reduction ability of gold is enhanced.At this time, chlorine and even concentrated nitric acid can oxidize Au to AuClfour-。Therefore, the main reason why aqua regia can dissolve gold is not that the oxidation ability of aqua regia is enhanced, but that the reduction ability of metal is enhanced.
Summary of reaction of aqua regia and other substances
Although there is still Cl in the aqua regiatwo、NOCl、NOtwoEqual strength oxidant, but no large amount of Cl-Ions exist, and they are not easy to oxidize Au, Pt, etcgoldGenus.
Storage
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The laboratory keeps aqua regia in brownGlass bottlesThe glass bottle is inserted in the sand pit.
Skin contact: in case of skin contact, immediately take off the contaminated clothes and wash with a large amount of flowing water for at least 15 minutes;If it is serious, seek medical advice immediately.
Eye contact: immediately open the eyelids and use plenty of flowing water ornormal salineFlush for at least 15 minutes, and seek medical advice in case of severe cases.
Inhalation: quickly leave the site to a place with fresh air to keep the respiratory tract unblocked, such asdyspnea, oxygen supply;asApnea, perform artificial respiration immediately (pay attention to whether mouth to mouth is feasible), and seek medical advice immediately.
Leakage disposal
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Evacuate the personnel in the leakage pollution area to the safety area, prohibit irrelevant personnel from entering the pollution area, and cut off the fire source.proposalEmergency ManagementSelf contained personnelrespirator, wearChemical protective clothing。Nodirect contact Leakage.Leak stoppage under the condition of ensuring safety.Do not allow leakage to interfere withCombustibleContact.Sprinkle soda ash on the ground.Then collect and transport towaste disposalSite disposal.A small amount of leakage is flushed with a large amount of water, and dilutedWashing waterInto the waste water system.In case of a large amount of leakage, the dike shall be used to collect it, and then it shall be collected, transferred, recycled or discarded after harmless treatment.
In the summer of 1996, the three were admitted to the Institute of Radiation Biology of Tsinghua University in Hsinchu, Taiwan (Hong and Xu were women in the master class, and Zeng was men in the doctor class)cram schoolThey became familiar with each other and became inseparable friends after they entered the university. However, they fell in love with Zeng Huantai, a fellow student at the same time, and gradually became hostile to each other.
Although Zeng Huantai said to the public that he only regarded the two girls as sisters and friends, in fact, Zeng Huantai had already had many separate incidents with the two girlsa sexual behavior。In the early morning of March 7, 1998, Hong Xiaohui and Xu Jiazhen negotiated in the lecture hall about Zeng Huantai. Hong Xiaohui asked Xu Jiazhen to give up Zeng Huantai. Xu Jiazhen was not satisfied. After a fierce dispute between the two, Hong Xiaohui slapped Xu Jiazhen, grabbed Xu Jiazhen's neck with both hands, and hit the ground, causing Xu Jiazhen's head to bleed heavily and finally became unconscious.
Hong Xiaohui takes a bottle from the laboratory“chloroform”Chemicals, Chao Xu JiazhenHindbrainShowering, hiding Xu Jiazhen in the lecture hallcold air machineAnd wipe the speech with gauzeIn front of the platformBlood stains.Sixteen hours after the crime, at 9:15 p.m. on March 7, Hong Xiaohui returned to the scene, shocked that Xu Jiazhen had inhaled "Geluofang" andPhotoreactionDecomposed“phosgene”He was suffocated and died, so he mixed nitric acid and hydrochloric acid into aqua regia in the laboratory of the Institute of Radiation Biology, and successfully destroyed the body with aqua regia. When Xu Jiazhen's body was found, his facial features were swollen and rotted beyond recognition.
Hong Xiaohui creates a doubt for this reason. At the scene of the murder case, she deliberately left a piece that Zeng Huantai used when she had sex with Zeng Huantai earlierCondoms, thrown under the left arm of the body, attempting to design the murder scene as Xu Jiazhen was sexually assaulted by gangsters.
2. HebeiCangzhouMs. Wang took jewelry to process and wanted to change the style.After processing, I found that,Gold ringThe weight of is 0.7g less.After testing, this bottle of liquid is the legendary "aqua regia" to melt the gold jewelry brought by consumers unknowingly.[2]
The shop owner explained that it was averagegoldWhen cleaning jewelry, first use fire to heat the gold to remove the oil stains on it, and then put the heated gold into hydrochloric acid solution for cleaning, so that the dust on the gold will be washed down without loss of gold itself.But he changed the cleaning solution into aqua regia and usedchemical reactionThe longer the immersion time is, the more gold will be stolen.
3. There are two scientists,LaueAnd Frank, who wonPhysics Award, GermanyNazi governmentTo confiscate their Nobel medals, they went back and forthDenmarkHe asked his Danish counterpart, Bohr, the winner of the 1922 Physics Prize, to help preserve it.In 1940,Nazi Germany Occupy Denmark and work with Bohr in the laboratoryHungarychemistHuvish(The winner of the 1943 chemistry prize) gave him an idea: put the medal in aqua regia (hydrochloric acid and nitric acidMixed liquid）The pure gold medal was dissolved.Bohr then put the solution bottle on the shelf of the laboratory, and the Nazi soldiers who came to search did not find the secret.
After the war, the gold in the solution bottle was restored and sent toStockholm, according to the current year'sMoldWhen he returned to Zhao in 1949, Frank worked in the United StatesChicagoThe city also held a grand medal returning ceremony.
