Lead IV Oxide

The lead IV oxide formula or the PbO₂ is the formula of an oxide where the oxidation state of lead is +4. Moreover, it is also known as the lead dioxide, or anhydrous Plumbic acid, or the Plumbic oxide. It is a strong oxidizing agent. The plumbic oxide is a dark-brown colour crystalline powder that is insoluble inside the water and the alcohol. It dissolves in the dilute nitric acid, hydrochloric acid, oxalic acid, and various other acids as well. However, it is widely useful while making the explosives, matches, and the electrodes.

Structure

The exact and accurate mass and the monoisotopic mass of the Lead IV oxide is 239.966 g/mol. The amount of the hydrogen bond acceptors is equal to 2 and the number of the hydrogen bond donors is equal to 0. In addition, this compound is canonicalized and has a single covalently bonded unit.

Production

Chemical Processes

We obtain the lead dioxide or the lead IV oxide commercially by numerous methods, such as oxidation of red lead i.e. Pb₃O₄ in alkaline slurry in a chlorine atmosphere, reaction of the lead(II) acetate with the “chloride of lime” i.e. calcium hypochlorite, the reaction of Pb₃O₄ with the nitric acid affords the dioxide as well:

Pb₃O₄ + 4 HNO₃ → PbO₂ + 2 Pb(NO₃)₂ + 2 H₂O

The compound PbO₂ reacts with the sodium hydroxide to produce the hexahydroxoplumbate (IV) ion [Pb(OH)₆]₂−, soluble with the water.

Electrolysis

An alternate synthesis technique is electrochemical: the lead dioxide produces on pure lead, in the dilute sulfuric acid, when polarized anodically at the electrode potential near about +1.5 V at the room temperature level. We use this procedure for large-scale industrial production of the PbO₂ anodes.

The lead and copper electrodes then immerse in the sulfuric acid that is flowing at a rate of 5–10 L/min. The electrodeposition is carried out galvanostatically, by the application of a current of about 100 A/m2 for about 30 minutes.

Uses

1. The lead (IV) oxide is useful in the manufacturing process of rubber substitutes.
2. We also use it in making explosives.
3. It is also useful as a curing agent for the polysulfide.
4. We use it as an oxidizing agent in the process of manufacturing the dyes.
5. It is useful in electroplating copper.
6. We use it in the lead-acid storage batteries as well.
7. We use it in textiles as well.

Chemical Reactions

The lead (IV) oxide decomposes when we heat it. The reaction is:

PbO₂ → Pb₁₂O₁₉ → Pb₁₂O₁₇ → Pb₃O₄ → PbO

Health Hazards

The plumbic oxide is toxic when swallowed or inhaled by a living being. Moreover, when we heat this compound it produces corrosive, toxic, and irritating gases. Contact with this substance may result in severe burns to the skin and the eyes.

Solved Example for You

Question: A 38 percent solution of the sulphuric acid is used as the electrolyte. Where (Density=1.294 g mL-1) the battery here is holding about 3.5 L of the acid. At the time of discharge of the battery, the density of the H₂SO₄ falls to 1.139 g mL-1.

What amount of electricity do we require in terms of Faraday to carry out the reduction of 1 mole of the PbO₂?

Solution: The Pb has the oxidation state of +4 in the PbO₂ and it reduces to PbSO₄ where the oxidation state is +2. Thus, 2 electrons (+4 – +2) electrons are the amount that we need here for this reduction reaction to occur:

Pb₄⁺ + 2e- → Pb₂⁺

Since the 2 electrons are welcome, are used up in this process of reduction, so by Faraday’s law of electrolysis:

1 mole of the Pb needs 2F electricity to carry out the process of reduction.