Which of the following changes will increase the emf of the cell :
`Co(s) | CoCl_2 (M_1)|| HCl(M_2) |Pt(H_2,g)`

Options

A. increase the volume of `CoCl_2` solution from 100 mL to 200 ml
B. increase `M_2` from 0.01 M to 0.50 M
C. increase the pressure of the `H_2(g)` from 1.00 to 2.00 atm
D. increase `M_1` from 0.01 M to ` 0.50 M`

Answer

A, B

Explanation

`=Co +2H^(+) + 2Cl^(-) to H_2 + Co^(+2) + 2Cl^(Ɵ) , E = E^(0) + (0.0591)/(2) log ""([H^(+)])/(P_(H_2) xx [Co^(+2)])`
`[{:([Co^(+2) ] = n//v),(v uarr [Co^(+2)] darr):}]= (4 xx 0.059)/(2) , = 0.118 = 0.12`