Lead Nitrate. Chemical properties, application

Lead nitrate is an inorganic compound having the following formula: Pb (NO3) 2. In the usual state it is a white powder or colorless crystals. This substance is very soluble in water.

Physical properties

1. It dissolves well with heat absorption in H2O (water), poorly in acetone, and also in methyl and ethyl alcohols.
2. Forms diamagnetic colorless crystals, density of 4.530 g / cm3. Each Pb atom (lead) is surrounded by twelve O atoms (oxygen). The bond length of Pb-O is 0.281 nm, and NO is 0.127 nm. Represents a cubic syngony. It belongs to the space group Pa3. In addition to the cubic variety, a monoclinic form was also obtained which, even when heated, is poorly soluble in H2O (water).
3. Lead, the melting point is 600.65 K.

How to get lead nitrate

This substance is not found in nature. Therefore, people have created some methods (industrial and laboratory), which are reduced to the dissolution of lead (Pb), its hydroxide or oxide in dilute nitric acid. Reactions:
3Pb (lead) + 8HNO3 (nitric acid) = 3Pb (NO3) 2 (lead nitrate) + 2NO (nitrogen oxide, released as gas) + 4H2O (water);
PbO (lead oxide) + 2HNO3 (nitric acid) = Pb (NO3) 2 (lead nitrate) + H2O (water);
Pb (OH) 2 (lead hydroxide) + 2HNO3 (nitric acid) = Pb (NO3) 2 (lead dinitrate) + 3H2O (water).

In order to suppress hydrolysis and reduce the solubility of lead dinitrate, nitric acid must be taken in excess.

Also lead dinitrate is obtained as a by-product in the purification of waste by a nitric acid, for example, in the treatment of bismuth-lead waste in factories. Later this compound is used for cyanidation of gold.

What are the chemical properties of lead nitrate

1. In an aqueous solution, lead nitrate dissociates into nitrate anions and lead cations. This is what this reaction looks like:

Pb (NO3) 2 (lead dinitrate) = Pb2 + (lead cation) + 2NO3- (anion of nitric oxide)

The solution of lead dinitrate is hydrolyzed. With an excess of NO3-, nitrate complexes are formed: [Pb (NO3) 6] 3-, [Pb (NO3) 4] 2- and [Pb (NO3) 3] -. If the pH of the solution is increased, the result is the formation of Pb (OH) x (NO3) y hydro- nitrates of variable composition. Some of them are isolated in the solid state.

2. Since lead dinitrate is a soluble compound, the following exchange reactions can be obtained:

2HCl (hydrochloric acid) + Pb (NO3) 2 = PbCl2 (lead chloride precipitates) + 2HNO3 (nitric acid);
H2SO4 (sulfuric acid) + Pb (NO3) 2 = PbSO4 (lead sulphate precipitates) + 2HNO3 (nitric acid);
Pb (NO3) 2 (lead nitrate) + 2NaOH (sodium hydroxide) = Pb (OH) 2 (lead hydroxide, precipitated) + 2NaNO3 (sodium nitrate);
Pb (NO3) 2 + 2NaN3 (sodium azide) = Pb (N3) 2 (lead azide, precipitated) + 2NaNO3 (sodium nitrate).

Any chemical compound containing a lead cation (Pb + 2) will react with a solution in which there is an anion of iodide. A yellow-orange precipitate is formed (Pbl2, lead iodide). This reaction looks like this:

Pb2 + + 2l- = Pbl2 (precipitate)

The same reaction occurs in the solid phase. For example:

Pb (NO3) 2 + 2Kl (potassium) = Pbl2 (precipitate) + 2KNO3 (potassium nitrate)

The use of lead nitrate

- used as an initial raw material for the production of most other Pb compounds (lead);
- as an inhibitor of nylon polymers and some other polyesters, as a zooid, in photothermographic paper coatings;
- Since lead nitrate is a potentially dangerous compound, other compounds are currently used in the industrial sector. For example, in the production of paints, matches and fireworks, lead compounds were completely abandoned.
- in the laboratory practice of lead, nitrate is used as a good and convenient source of tetraoxide diazotide;
- relatively recently in very limited quantities, this chemical compound is used in the cyanidation of gold.
- in organic chemistry, Pb (NO3) 2 is used as an oxidant for the preparation of isothiocyanates from dithiocarbamates. Because of its high toxicity, it is used less and less.

Security

Lead Nitrate is classified as Category 2A (probably a carcinogenic compound for humans). It is unacceptable to inhale its toxic fumes or ingestion, and also contact with skin or mucous membranes. Lead dinitrate should be constantly under control. Poisoning this chemical compound leads to poisoning, gliomas and cancer of the kidneys, brain and lungs.