NEW
New Website Launch
Experience the best way to solve previous year questions with mock tests (very detailed analysis), bookmark your favourite questions, practice etc...
1

### AIPMT 2000

For the disproportionation of copper
2Cu+  $$\to$$ Cu2+ + Cu, Eo is
(Given Eo for Cu2+/Cu is 0.34 V and
Eo for Cu2+/Cu+ is 0.15 V.)
A
0.49 V
B
$$-$$ 0.19 V
C
0.38 V
D
$$-$$0.38 V

## Explanation

Cu2+ + 2e $$\to$$ Cu; E°1 = 0.34 V .....(1)

Cu2+ + e $$\to$$ Cu+ ; E°2 = 0.15 V.....(2)

Cu+ + e $$\to$$ Cu; E°3 = ? .....(3)

$$\therefore$$ $$\Delta$$Go1 = -2$$\times$$0.34$$\times$$F

and $$\Delta$$Go2 = -1$$\times$$0.15$$\times$$F

and $$\Delta$$Go3 = -1$$\times$$E°3$$\times$$F

Also, $$\Delta$$Go1 = $$\Delta$$Go2 + $$\Delta$$Go3

$$\Rightarrow$$ -0.68F = -0.15F - E°3 $$\times$$ F

$$\Rightarrow$$ E°3 = 0 68 - 0 15 = 0 53 V

$$\therefore$$ E°cell = 0.53 - 0.15 = 0.38 V
2

### AIPMT 2000

Equivalent conductances of Ba2+ and Cl$$-$$ ions are 127 and 76 ohm$$-$$1 cm$$-$$1 eq$$-$$1 respectively. Equivalent conductance of BaCl2 at infinite dilution is
A
139.5
B
101.5
C
203
D
279

## Explanation

According to Kohlrausch’s law, the equivalent conductance of BaCl2 at infinite dilution,

$$\lambda$$$$\infty$$ of BaCl2 = $${1 \over 2}$$$$\lambda$$$$\infty$$ of Ba2+ + $$\lambda$$$$\infty$$ of Cl-

$$\Rightarrow$$ $$\lambda$$$$\infty$$ of BaCl2 = $${1 \over 2} \times 127 + 76$$ = 139 5

### Joint Entrance Examination

JEE Main JEE Advanced WB JEE

### Graduate Aptitude Test in Engineering

GATE CSE GATE ECE GATE EE GATE ME GATE CE GATE PI GATE IN

NEET

Class 12