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Standard XII

Chemistry

Factors Affecting Corrosion

In corrosion ...

Question

In corrosion of iron,

electrons flow from anode to cathode through the metal, while ions flow through the water droplets

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an electrochemical (galvanic) cell is formed in which

F e

acts as anode and

O_{2}

is reduced at cathode

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dissolved

O_{2}

oxidizes

F e^{2 +}

F e^{3 +}

before it is deposited as rust

(F e_{2} O_{3} . x H_{2} O)

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All of the above takes place

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Solution

The correct option is B All of the above takes place
The corrosion of iron is an electrochemical process. The anode region and cathode region are present in iron. $I r o n (I I)$ is oxidized to $I r o n (I I I)$ by oxygen and is then converted to rust. At the cathode, oxygen is reduced. The electron flow is from anode to cathode through metal.
This is accompanied by the flow of ions through water droplets.

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Similar questions

Q. Assertion :Fe is protected from corrosion by connecting Mg metal with it. Reason: Fe acts as cathode and Mg as anode which gradually disappears.

In electrolytic cell flow of electron is from :
a)cathod to anode in solution
b)cathode to anode through external supply
c)cathode to anode through internal supply
d)anode to cathode to internal supply

[Pls explain Concept and answer]

Q. When a galvanic cell is connected to an external volatge supply (

E_{e x t}

), the electrons flow from cathode to anode because

Electrochemical Battery

An electrochemical battery is a device powered by oxidation and reduction reactions that are physically separated. So that the electrons must travel through a wire from the reducing agent to the oxidizing agent.

The reducing agent loses electrons and is oxidized in a reaction that takes place at an electrode is called the anode. The oxidizing agent gains electrons and is reduced in a reaction that takes at an electrode is called the cathode.

To maintain a net zero charge in each compartment, there is a limited flow of ions through a salt bridge.

For example, in a car battery the reducing agent is oxidized by the following reaction, which involves a lead (

P b

) anode and sulfuric acid (

H_{2} S O_{4}

). Lead sulfate (

P b S O_{4}

), protons (

H

), and electrons (

e^{-}

) are produced.

At the cathode, the below reaction occurs :

P b O_{2} + H_{2} S O_{4} + 2 H^{+} + 2 e^{-} \to

PbSO_4+2H_2O$

At the anode, the below reaction occurs :

P b + H_{2} S O_{4} \to P b S O_{4} + 2 H^{+} + 2 e^{-}

Electrons are produced by a chemical reaction that takes place at the:

(a) Here is an electrode reaction :

$C u \to C u^{2 +} + 2 e^{-}$ . At which electrode (anode or cathode) would such a reaction take place? Is this an example of oxidation or reduction ?

(b) A solution contains magnesium ions $(M g^{2 +})$ , iron (II) ions $F e^{2 +}$ and copper ions $C u^{2 +}$ . On passing an electric current through this solution, which ions will be the first to be discharged at the cathode? Write the equation for the cathode reaction.

(d) During the electrolysis of molten lead bromide, which of the following takes place ?

A. Bromine is released at the cathode,

B. Lead is deposited at the anode,

C. Bromine ions gain electrons,

D. Lead is deposited at the cathode.

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