Lead Acetate

What is Lead Acetate?

Lead acetate is an ionic compound with the formula [Pb(CH3COO)2], in which lead is present in +2 oxidation state. It is a white crystalline solid. It has a slight sweet taste.  It is also known as Plumbous acetate, salt of Saturn, sugar of lead, Goulard’s powder or lead diacetate. Its systematic IUPAC name is Lead(II) ethanoate. Lead acetate is also toxic like other lead compounds. But it still has various applications such as a fixative and also as a reagent for synthesis of other compounds. It was also used as a sweetener but soon it was banned due to its toxic nature. It was discovered in the US in 1944. 

Lead(II) acetate has Pb+2 cation and CH3COO- anion. It is a water - soluble compound. It is commonly found as trihydrate lead acetate which is particularly known as sugar of lead due to its sweet taste. Molecular formula of trihydrate lead acetate is Pb(CH3COO)2.3H2O. It is white in color and a monoclinic crystalline substance which is soluble in water. It is used in dyeing, gold cyanidation plants, paints etc.

 

Formula of Lead(II) Acetate

S. No.

IUPAC Name & Formula of Lead(II) Acetate

1.

Empirical Formula 

PbC4H6O4

2.

Molecular Formula 

Pb(C2H3O2)2 or [Pb(CH3COO)2]

3.

Skeletal formula

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4. 

IUPAC name 

Lead(II) ethanoate 

5. 

Other general names 

Plumbous acetate, salt of Saturn, lead acetate, sugar of lead, Goulard’s powder, lead diacetate


Structure of Lead Acetate 

It is an ionic compound which is formed by the reaction of elemental lead and acetic acid. It has one Pb2+ ion and two CH3COO- ions. As lead cation contains +2 charge while each acetate anion has -1 charge, so the compound lead(II) acetate contains zero charge. 

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Properties of Lead Acetate 

Physical and chemical properties of lead acetate - Properties of lead acetate are listed below –

  • Molar mass of anhydrous lead acetate is 325.29 g.mol-1.

  • Molar mass of its trihydrate (Pb(CH3COO)2.3H2O) form is 379.33 g.mol-1.

  • It is a white colored efflorescent crystalline solid. 

  • It is slightly sweet in taste.

  • It has a pleasant acetic smell. 

  • Its density in its anhydrous form is 3.25 g.cm-3 while in its trihydrate form is 2.55 g.cm-3.

  • Melting point of anhydrous lead acetate is 280 °C. While melting point of trihydrate lead acetate is 75 °C.

  • Anhydrous lead acetate is soluble in water and its solubility increases as temperature increases. For example, 19.8 gram of it is soluble in 100ml water at 0 °C while 44.3 grams are soluble in 100ml water at 20 °C.

  • It is also soluble in alcohol, glycerol etc. 

  • It is highly soluble in methanol. For example, at 66.1 °C temperature, 102.75 grams of lead acetate is soluble in 100 grams of methanol. 

  • Its 20 grams are soluble in 100 g of glycerol at 15 °C.

  • It has monoclinic crystal structure. 

  • It is a non – flammable but toxic compound. On oral consumption, 400mg/kg of it can be lethal for mice. 

  • It is basic in nature. 

  • Its standard enthalpy of formation is -960.9 kJ.mol-1.

  • Reaction with hydrogen sulfide – It reacts with hydrogen sulfide and forms lead sulfide and acetic acid. Reaction is given below –

Pb(C2H3O2)2 + H2S → PbS + 2CH3COOH

  • Reaction with potassium chromate – It reacts with potassium chromate and forms lead chromate and potassium acetate. Reaction is given below –

K2CrO4 + Pb(C2H3O2)2 → PbCrO4 + 2CH3COOK


Production of Lead Acetate 

It can be produced by following two methods –

  • By reaction of acetic acid, hydrogen peroxide and elemental lead

  • By reaction of copper acetate and lead metal

By reaction of acetic acid, hydrogen peroxide and elemental lead – Elemental lead is boiled in acetic acid and hydrogen peroxide which result into lead acetate and water. Lead carbonate or lead oxide can be used in place of elemental lead. Reaction is given below –

Pb(s) + H2O2(aq) + 2H+(aq) → Pb2+(aq) + 2H2O(l)

Pb2+(aq) + 2CH3COO(aq) → Pb(CH3COO)2(aq)

By reaction of copper acetate and lead metal – Lead metal on reaction with copper acetate displaces copper metal and forms lead acetate by single displacement reaction. The equation is given below –

Cu(CH3COO)2 + Pb → Cu + Pb(CH3COO)2


Uses of Lead Acetate 

Lead acetate was used as a sweetener due to its slight sweet taste. Ancient Romans used to boil grape juice in lead pots to produce reduced sugar syrup. This sugar syrup was called defrutum. But after a few years it was recognized that lead compounds (or lead acetate) are toxic and were causing lead poisoning in those who were consuming the sugar syrup. Currently, its usage as a sweetener is banned. 

Lead acetate has been widely used in the cosmetic industry for a long time but due to its toxicity, presently its use has been limited. Nowadays it is mainly used in production of hair coloring products. Although in many places such as Canada, European Union and California lead acetate is completely banned in food items and cosmetic products as well due its carcinogenicity and reproductive toxicity. It was also used as a remedy for sore nipples. 

Lead acetate solution which is also known as Goulard’s Extract is used as an astringent to constrict mucous membrane and exposed tissues in modern medicine. Specifically, Goulard’s extract is a solution of lead acetate and lead oxide which was first introduced by French surgeon Thomas Goulard. 

A paper made up of lead acetate is used in detection of poisonous gas H2S. Moist lead acetate on reaction with hydrogen sulfide gas gives lead sulfide. 

It is also used in cleaning and maintenance of stainless steel suppressors and compensators. It was also used in making matchsticks during the Medieval period. Sugar of lead is used in boiled linseed oil to increase its effectiveness. 


Lead(II) Acetate: Summary in Tabular Form 

Lead(II) Acetate 

Chemical Formula 

Pb(C2H3O2)2 or [Pb(CH3COO)2]

IUPAC Name 

Lead(II) ethanoate 

Other Names 

Plumbous acetate, salt of Saturn, lead acetate, sugar of lead, Goulard’s powder, lead diacetate

Molar Mass 

325.29 g/mol (anhydrous lead acetate)

379.33 g/mol (trihydrate lead acetate)

Melting point 

280 °C (anhydrous)

75 °C (trihydrate)

Boiling Point 

Trihydrate lead acetate gets decomposes at 200 °C or above.

Density 

3.25 g.cm-3 (anhydrous)

2.55 g.cm-3 (trihydrate)

Appearance 

Colorless White crystalline solid

Odor 

Acetic smell 

State at STP

Solid 

Taste 

Sweet 

Solubility in Water 

It is highly soluble in water 

Solubility in Methanol (or alcohol)

It is highly soluble in methanol (102.75 g/100 g at 66.1 °C)

Solubility in Glycerol

It is soluble in glycerol. 

Nature 

Basic 

Preparation 

By reaction of acetic acid, hydrogen peroxide and elemental lead. 

Pb(s) + H2O2(aq) + 2H+(aq) → Pb2+(aq) + 2H2O(l)

Pb2+(aq) + 2CH3COO(aq) → Pb(CH3COO)2(aq) 

 Another method – by single displacement reaction between copper acetate and lead. 

Cu(CH3COO)2 + Pb → Cu + Pb(CH3COO)2

Main Properties 

It is sweet in taste.

It is soluble in water, alcohol and glycerol. 

Main Use 

In hair coloring and as reagent to make other lead compounds.  

Disadvantage 

It is a toxic compound.  


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