Question

It took 150. s for a current of 1.25 A to plate out 0.109 g

of metal from a solution containing its cations. Show

that it is not possible for the cations to have a charge

of +1.

Short answer

The molar mass when calculated Is 56g/mol which is of iron in the periodic table, and iron(Fe) which can only exist as Fe²⁺or Fe³⁺and it does not exist as 1+

Step-by-step solution

analyzing the given data

Amount of current= 1.25 A

Amount of metal= 0.109g

Time is taken by current of 1,25 A to plate 0.109g metal= 150 s

Explaining why the cation can’t have a charge of 1+  

Let M be the metal and n be the charge on it.

${M^{n+}}_{(Ag)}+nelectrons\to M_{\left(S\right)}$

$$\begin{gathered} \frac{1.25C}{5}\times 150s\times \frac{1{\text{molee}}^{-}}{96485\text{C}}=0.001943mole \\ let\text{n = 1,} \\ \frac{.209\text{g}}{0.001943\text{mole of M}}=56\text{g/mol} \end{gathered}$$

56 g/mol is the molar mass of iron (Fe) which can only exist as Fe²⁺or Fe³⁺and it does not exist as 1+

Since this is the molar mass of iron, hence n can never be 1+ and so the cations can’t have a charge of 1+.