Question

2g equivalent of Na metal is formed from electrolysis of fused NaCl.Moles of Al from fused Na_(3)AlF_(6) formed by passage of same amount of charge (assume at cathode only Al deposited) is x .Then value of 3x is​

Answer 1

Answer:  x = 0.0145 mole of Al and 3x = 0.0434 mole of Al

Explanation:

Na⁺ + Cl⁻ → NaCl

96500 Coulombs of electricity liberates = 1 mole of Na⁺ or 23 gm equivalents of Na⁺

So, 1 gm equivalent of Na⁺ will be liberated by = 96500/23 = 4195.65 Coulombs

It is said that same amount of charge or electricity is used in the formation of Na₃AlF₆ by electrolysis.

Hence,

96500 Coulombs = 1 mole of e⁻

4195.65 Coulombs = 1 mole of e⁻ × 4195.65 / 96500

that is, 0.0434 mole of e⁻

Also,

Al³⁺ + 3e⁻ → Al (metal)

Therefore, 0.0434 mole of e⁻ × (1/3) mole of Al

= 0.0145 mole of Al.

Thus, x = 0.0145 mole of Al

and 3x = 0.0434 mole of Al

Answer 2

Answer:

The value of x is 2/3 and the value of 3x is 2.

Explanation:

Na⁺ + Cl⁻ → NaCl

By Faraday's law

∴ Equivalent of Na = Equivalent of Al

Moles of Na × n = Moles of Al × n

2 × 1 = x × 3

x= 2/3

Therefore, the no. of moles of Al is x= 2/3

Hence the value of 3x is

2/3 × 3 = 2

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