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For the cell prepared from electrodes A ...

For the cell prepared from electrodes A and B,
Electrode A :`Cr_2O_7^(2-)//Cr^(3+),E_"red"^@=1.33 V` and Electrode B: `Fe^(3+)//Fe^(2+), E_"red"^@=0.77 V`
Which of the following statements is correct?

A

The electrons will flow from B to A when connections are made.

B

The standard EMF of the cell will be 0.56 V.

C

A will be a positive electrode.

D

All of these.

Text Solution

Verified by Experts

The correct Answer is:
D
`E_(RP(Cr_2O_7^(2-)//Cr^(3+)))^@`=1.33 V and `E_(RP(Fe^(3+)//Fe^(2+)))^@`=0.77 V
`therefore E_(RP(Cr_2O_7^(2-)//Cr^(3+)))^@` is more positive than `E_(RP(Fe^(3+)//Fe^(2+)))^@` thus, `Cr_2O_7^(2-)` will undergo reduction and `Fe^(2+)` will undergo oxidation so, electrons will flow from Fe electrode to Cr electrode . Also, Fe electrode will be negative electrode .
Also ,`E_"cell"^@=E_(RP(Cr_2O_7^(2-)//Cr^(3+)))^@-E_(RP(Fe^(3+)//Fe^(2+)))` =1.33-0.77 = 0.56 V
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