1 N2O colorless gas
No colorless gas.
SP hybridization, paramagnetic
It is a blue liquid at 3 N 2O 3 0℃.
N2O3 is the anhydride of HNO2, and it is a blue liquid at 273K.
4 NO2
NO2 is brownish red gas, N-unequal hybridization, less big bond electrons, high bond order and good stability. As far as possible, there is no single electron in the hybrid orbit, and the energy is too high, so the non-bonded hybrid orbit has a pair of electrons and the non-hybrid Pz orbit has a single electron.
N2O4 is a mixed anhydride.
The white solid of 5 N2O5 is the anhydride of HNO3, and the structure of gas molecule:
2. Nitrite and its salts
Molecular structure of 1 nitrite
Generally speaking, trans structure is more stable than cis structure. Because the double bonds O and OH are on both sides, mutual repulsion is small and stable.
In HNO2 _ 2 molecule, N hybridizes with SP2 inequality, forming two σ bonds on two O's,
The lone electron pair of n occupies the hybrid orbit, and the Pz orbit has 1 electron, which is connected with the end group.
Pz 1 of oxygen overlap side by side to form π bond.
N of NO2- hybridizes with SP2 inequality to form two σ bonds. N also has a Pz 1 orbit, and two O's each have a Pz 1, which is formed by adding an external electron.
2 chemical properties
In acidic medium, it can be seen from the free energy oxidation diagram that HNO2 is located above the connecting line between HNO3 and NO. From the thermodynamic point of view, HNO2 _ 2 is unstable, and it is also unstable in dynamics. HNO2 only exists in aqueous solution, and no free acid has ever been obtained, so HNO2 is prone to disproportionation and decomposition.
Stable in alkaline medium, it can be inferred that nitrite can exist stably.
B) weak acidity
The existing form in strong acid is
C) redox properties
N in HNO2 is valence +3, so it is both oxidized and reduced.
In acidic medium: HNO _ 2/NO = 0.99 V, it has strong oxidation ability.
Because there is NO+in the acid, it is easy to change electrons into NO, so it is easy to oxidize I-. This is the difference between nitrous acid and dilute nitric acid. Due to the above kinetic reasons, the acidic solution of nitrate can not oxidize I-. In the case of strong oxidants, it is also reducible.
Without oxidant and reductant, it is easy to be out of proportion.
D) insoluble salts and complexes
Except for light yellow AgNO2, other salts are generally soluble. Cobalt salt is added into the solution of nitrite and potassium nitrite to form complex ions, and its potassium salt K3[Co(NO2)6] is yellow precipitate. Nitrite is an unstable weak acid with oxidation and reduction ability, but mainly oxidation and complexing ability.
3 degree preparation
Introducing the mixture of NO and NO2 into ice water to obtain HNO2.
NO2+NO+H2O-2hNO2 blue
When the temperature is high, HNO2 _ 2 is unstable and decomposed by heating.
3. Nitric acid and its salts
Structure of 1 nitric acid and its nitrate radical
2 the nature of nitric acid
B: Unstable.
Nitric acid-4NO2+2H2O+O2
The boiling point of HNO _ 3 is 356K K, and HNO _ 3 gradually decomposes after reaching the boiling point, and also decomposes when it sees light. So keep it away from light.
2NHO3-N2O5+H2O (smog)
2 HNO 3+ strong dehydrating agent = N2O5+H2O N2O5 is the anhydride of HNO3.
C: oxidizability
Most of the reduction products of the reaction between concentrated nitric acid and metal are NO2, which can catalyze the oxidation of nitric acid.
Copper+nitric acid = copper nitrate+2NO2 +2 H2O
Most reduction products of concentrated nitric acid and nonmetal are NO.
Sulfur+nitric acid (concentrated) = sulfuric acid+nitric acid
Dilute nitric acid reacts with reducing agent, and the product has no certificate.
The thinner HNO3 is, the lower the reduced valence state is, the more active the metal is, and the lower the valence state of the product is.
Zinc+nitric acid (diluted) = zinc (nitric acid) 2+ ammonium nitrate +H2O.
Methods for detecting NH4+:
Because of the different concentrations of nitric acid, the reduction products may be N2O and N2, and the extremely dilute nitric acid hardly oxidizes.
Manganese sulfate+nitric acid (extremely dilute)-manganese nitrate +H2S
Although concentrated nitric acid is highly oxidizing, gold is still very stable in concentrated nitric acid. Dissolved in royal water.
Oxidation of aqua regia
Concentrated nitric acid: concentrated hydrochloric acid = 1: 3 (volume ratio)
At this time, Au can be dissolved when HNO3 is slightly concentrated, so the oxidation ability of aqua regia is not stronger than HNO3, but aqua regia reduces the potential of metals, so aqua regia can dissolve precious metals such as Au and Pt.
Au + HNO3 + 4HCl - HAuCl4 + NO + 2H2O
React with Pt to generate H2PtCl6.
3 thermal decomposition of nitrate
The electric field of cationic ions is weak, and nitrous acid can still exist stably, so the product of nitrate thermal decomposition is nitrite.
The electric field of nitrate with potential between cation Mg2+ is strong, and nitrite is unstable, so NO2 and O2 must be decomposed and released.
Cationic oxides of mercury, silver and gold are unstable and decompose.
Reducing cation NH4NO3-N2O+H2O
Generally, nitrate releases O2, so it can support combustion.
When nitrate and crystal water are heated, hydrolysis will occur.
4 preparation of nitric acid
Nitric acid is produced by NH3 oxidation in industry.
Laboratory methods:
Nitric acid is volatile and can be prepared by the reaction of sodium nitrite and concentrated sulfuric acid.