When the zinc plate in one of Edison's coulometers increased in mass by 7.85 g, the amount of charge that had passed through it is 23,173 C.
The zinc metal will ionize as shown below;
Zn²₊ + 2e⁻ → Zn
The molar mass of zinc metal is given as 65.38 g/mol
Amount of charge that will deposite the given mass of zinc is calculated as follows;
e⁻ = 96500 C
2e⁻ = 2 x 96500 C = 193,000 C
65.38 g -------> 193,000 C
7.85 g -----------> ?
= (7.85 x 193,000)/(65.38)
= 23,173 C
Thus, when the zinc plate in one of Edison's coulometers increased in mass by 7.85 g, the amount of charge that had passed through it is 23,173 C.
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