lead nitrate - is an inorganic compound having the following formula: Pb (NO3) 2.In the normal state is a white powder or colorless crystals.This substance is readily soluble in water.
Physical properties
1. It dissolves with heat absorption in H2O (water), poor - in acetone, as well as methyl and ethyl alcohols.
2. Forms diamagnetic colorless crystals, density of 4.530 g / santimetr³.Every atom of Pb (lead) is surrounded by twelve atoms O (oxygen).Bond length Pb-O is 0.281 nm, and NO - 0,127 nm.It represents a cubic system.It belongs to the space group Pa3.Furthermore variety cube was obtained even monoclinic form which even when heated slightly soluble in H2O (water).
3. Lead melting point is 600,65 K.
How to get lead nitrate
This substance is not found in nature.Therefore, people have developed several methods (laboratory and commercial), which are reduced to the dissolution of lead (Pb), its oxide or hydroxide in dilute nitric acid.Reactions:
3Pb (lead) + 8HNO3 (nitric acid) = 3Pb (NO3) 2 (lead nitrate) + 2NO (nitrogen oxide is released as a gas) + 4H2O (water);
PbO (litharge) + 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).
order to suppress the hydrolysis and reduce the solubility of lead dinitrate, nitric acid should be taken in excess.
also lead dinitrate obtained as a byproduct in the purification of waste acid, nitric acid, for example, in the processing of lead-bismuth waste in plants.Further, this compound is used for cyanidation of gold.
What chemical properties have lead nitrate
1. In an aqueous solution of lead nitrate dissociates into anions and cations lead.Here is the reaction:
Pb (NO3) 2 (lead dinitrate) = Pb2 + (cation lead) + 2NO3- (nitric oxide anion)
lead dinitrate solution is subjected to hydrolysis.When an excess amount NO3- formed nitratokompleksy: [Pb (NO3) 6] 3-, [Pb (NO3) 4] 2- and [Pb (NO3) 3] -.If the pH of the solution increase, the result is created gidronitraty Pb (OH) x (NO3) y variable composition.Some of them are highlighted with a solid state.
2. Since lead dinitrate is soluble compound, it is possible to obtain the following exchange reaction:
2HCl (hydrochloric acid) + Pb (NO3) 2 = PbCl2 (lead chloride precipitates) + 2HNO3 (nitric acid);
H2SO4 (sulfuric acid) + Pb (NO3) 2 = PbSO4 (lead sulfate precipitates) + 2HNO3 (nitric acid);
Pb (NO3) 2 (lead nitrate) + 2NaOH (Sodium hydroxide) = Pb (OH) 2 (lead hydroxide precipitates) + 2NaNO3 (sodium nitrate);
Pb (NO3) 2 + 2NaN3 (sodium azide) = Pb (N3) 2 (lead azide, precipitates) + 2NaNO3 (sodium nitrate).
Any chemical compound containing a lead cation (Pb + 2) will react with a solution in which there is iodide anion.So as to precipitate a yellow-orange color (Pbl2, lead iodide).It looks like this reaction:
Pb2 + + 2l- = Pbl2 (pellet)
same exchange reaction in the solid phase.For example:
Pb (NO3) 2 + 2Kl (potassium) = Pbl2 (precipitates) + 2KNO3 (potassium nitrate)
Application of lead nitrate
- is used as a primary raw material for the production of most other compounds Pb (lead);
- as inhibitor of nylon polymers and other polyesters as a rodenticide, fototermograficheskoy paper coatings;
- since the lead nitrate - is for quite a dangerous compound in industrial applications now use other compounds.For example, in the manufacture of paints, matches and fireworks completely abandoned lead compounds.
- in the laboratory of lead nitrate is used as a good and convenient source of dinitrogen tetroxide;
- relatively recently in very limited quantities of a chemical compound used in the cyanidation of gold.
- in Organic Chemistry, Pb (NO3) 2 is used as an oxidant to obtain from dithiocarbamates isothiocyanates.Because of its high toxicity it is used less and less.
Security
lead nitrate is classified as a category 2A (probably carcinogenic compounds to humans).It is unacceptable to the inhalation of toxic fumes or ingestion and contact with skin or mucous membranes.Dinitrate lead must remain under control.Poisoning by this chemical compound leads to poisoning, glioma and cancer of the kidneys, brain and lungs.
