[Chemistry Class Notes] Lead Acetate Pdf for Exam

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.

 

The formula of Lead(II) Acetate

 

Structure of Lead Acetate 

It is an ionic compound that 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 charges. 

 

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Properties of Lead Acetate 

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

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

• The 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.

• 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.

• The melting point of anhydrous lead acetate is 280 °C. While the 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 grams 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 a monoclinic crystal structure. 

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

• It is basic. 

• 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. The reaction is given below –

Pb(C2H3O2)2 + H2S → PbS + 2CH3COOH

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

 

Production of Lead Acetate 

It can be produced by following two methods –

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

• By the reaction of copper acetate and lead metal

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

 

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

 

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

 

By the reaction of copper acetate and lead metal – Lead metal on reaction with copper acetate displaces copper metal and forms lead acetate by a 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 slightly 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 the 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 to 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 the detection of poisonous gas H2S. Moist lead acetate on reaction with hydrogen sulfide gas gives lead sulfide. 

 

It is also used in the 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 

 

Conclusion:

This ends our coverage on the topic “lead acetate”. We hope you enjoyed learning and were able to grasp the concepts. We hope after reading this article you will be able to solve problems based on the topic.

 

The formula of Lead Acetate:

Lead acetate is a white crystalline compound with a chemical formula Pb(C2H3O2)2.

 

Structure of Lead Acetate:

 

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Properties of Lead Acetate:

 

Production of Lead Acetate:

Lead acetate can be made by boiling elemental lead in acetic acid and hydrogen peroxide. This method will also work with lead carbonate or lead oxide.

 

Pb_(s) + H2O2_(aq) + 2 H+_(aq) → Pb2+_(aq) + 2 H2O_(l)

 

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

 

Lead(II) acetate can also be made via a single displacement reaction between copper acetate and lead metal:

 

Cu(CH3COO)2 + Pb → Cu + Pb(CH3COO)2

 

Uses of Lead Acetate:

Sweetener: Similar to other lead (II) salts. Lead acetate (II)  has a sweet taste and has historically been used as a sugar substitute for wine and food. The ancient Romans, who had few sweeteners other than honey, boiled must (grape juice) in a reed pot to make a sugar-reduced syrup called syrup, which was concentrated and returned to Sapa. This syrup was used to sweeten wine and  sweeten and preserve fruits. Lead (II) acetate or other lead compounds in the syrup may have caused lead poisoning in those who ingested it. Lead acetate has been shown to be toxic and is no longer used in the production of sweeteners. 

Modern chemistry can easily see it and has almost completely stopped its illegal use, which has continued for decades since its use as a sweetener was banned. Cosmetics: Lead acetate (II) and white lead have been used in cosmetics throughout history.  Medical Use: Lead (II) Acetate Solution is a common folk remedy for nipple pain. In modern medicine,  it was sometimes used as an astringent, in the form of a gall extract, and  also  to treat poison ivy.  Industrial Use: Lead (II) acetate paper is used to detect the toxic gas hydrogen sulfide. The gas reacts with lead (II) acetate on  moistened test strips to form a gray precipitate of lead (II) sulfide.