Chemical reactions

Reaction of lead with acids

Lead does not react with sulphuric acid, due to the passivated PbO surface.

Lead reacts slowly with hydrochloric acid, HCl and nitric acid, HNO3.

Pb(s) + 2 HCl(aq) Pb2+(aq) + 2 Cl(aq) + H2(g)
Pb(s) + 2 HNO3(aq) Pb2+(aq) + 2 NO3(aq) + H2(g)

Reaction of lead with air

Lead reacts with air, in the presence of moist and carbon dioxide, forming a passivating layer. The layer is most likely lead hydroxy carbonate [8].

When heated in a stream of air, lead burns [8]:

2 Pb(s) + O2(g) 2 PbO(s)

Reaction of lead with bases

Lead dissolves slowly in cold alkalis to form plumbites.

Pb(II) reacts with hydroxide forming lead(II) oxide. The oxide is soluble in excess hydroxide, forming a lead hydroxide complex

Pb2+(aq) + 2 OH(aq) + x H2O(l) PbO · (x+1) H2O(s)

PbO · x H2O(s) + OH(aq) [Pb(OH)3](aq) + (x-1) H2O(l)

Reaction of lead with chromates

Lead(II) is precipitated by chromate under acidic conditions.

Pb2+(aq) + CrO42−(aq) PbCrO4(s) [yellow]

Reaction of lead with halogens

Lead reacts vigorously with fluorine, F2, at room temperature, and chlorine, Cl2, when heated, forming the corresponding lead(II) halides [8].

Pb(s) + F2(g) PbF2(s)
Pb(s) + Cl2(g) PbCl2(s)

Lead(II) is precipitated by chloride, bromide and iodide ions under cold neutral to acidic conditions. In concentrated hydrochloric acid, the chloride precipitate is dissolved. Solubility of the salts decrease with increasing periods:

Pb2+(aq) + 2 Cl(aq) PbCl2(s) [white]
PbCl2(s) + 2 Cl(aq) [PbCl4](aq)

Pb2+(aq) + 2 Br(aq) PbBr2(s) [white]

Pb2+(aq) + 2 I(aq) PbI2(s) [yellow]

Reaction of lead with metals/metal ions

Lead(IV) is a strong oxidizing agent:

PbO2(s) + 2 Ce3+(aq) + 4 H+(aq) + 12 NO3(aq) Pb2+(aq) + 2 [Ce(NO3)6]2−(aq) + 2 H2O(l)

2 Mn2+(aq) + 5 Pb3O4(s) + 24 H+(aq) MnO4(aq) + 15 Pb2+(aq) + 12 H2O(l)

Reaction of lead with sulfates

Lead(II) is precipitated by sulfate under neutral to acidic conditions. The precipitate is partially soluble in concentrated sulfuric acid and dilute nitric acid and highly soluble in hot sodium hydroxide or acetate buffer:

Pb2+(aq) + SO42−(aq) PbSO4(s) [white]
PbSO4(s) + 3 OH(aq) [Pb(OH)3](aq) + SO42−(aq)
Pb2+(aq) + 2 Ac(aq) PbAc2(aq) + SO42−(aq)

Reaction of lead with sulfides

Lead(II) is precipitated by sulfide in 0.4 M hydrochloric acid. During the process, red or brown intermediates can sometimes be observed:

Pb2+(aq) + H2S(aq) PbS(s) [black] + H2(g)

Reaction of lead with sulfur

When heated, lead reacts with sulfur [8]:

Pb(s) + S(s) PbS(s)

Reaction of lead with water

Lead does not react with water in the absence of air. In the presence of air, lead(II) hydroxide is formed [8]:

2 Pb(2) + 2 H2O(l) + O2(g) 2 Pb(OH)2(s)

Quantitative analysis

Method 3500-Pb C Inductively Coupled Plasma Method [6]. A portion of the sample is digested in a combination of acids. The digest is aspirated into an 8,000 K argon plasma where resulting light emission is quantified for 30 elements simultaneously.

Method limit of detection in water = 0.01 mg/L
Method limit of detection in soil = 2.00 mg/kg