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Whatis the amount of silver deposited by passing 2 A for 20 min through molten silver nitrate ? If the same quantity of electricity is passed through a molten salt solution of gold, 1.6 g of gold is deposited at cathode, then find out its equivalent mass and oxidation state of gold in gold salt. (atomic weight of Au = 197, Ag = 108)

Answer»

Solution :Number of gram equivalents `= ("CURRENT "xx" time")/(96500)`
`= (2xx 20 xx 60)/(96,500) = 0.0248`
Amount of silver deposited `= 0.0248 xx 108 = 2.68g`
Let the equilvalent weight of Au be `E_(Au)`.
`:. (E_(Au))/(E_(HG)) = (W_(Au))/(W_(Ag))`
`rArr (E_(Au))/(108) = (1.6)/(2.68) rArr E_(Au) = 64.47`
`:.` Oxidation state of gold `= ("Atomic weight")/("Equivalent weight")`
`= (197)/(64.47)`
`= 3.05 ~~3`
Gold is present in `Au^(+3)` state in the salt


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