Question

Decribes the oxidising action of potassium dichromate and write the ionic equation for its reaction with:
A. iodide
B. iron solution and
C. `H_(2)S`
D. `H_(2)S`

Answer 1

Correct Answer - `({:(Cr_(2)O_(7)^(2-)+14H^(+)+6e^(-)to2Cr^(3+)+7H_(2)O),(2I_(2)toI_(2)+2e^(-)xx[3]):})/(Cr_(2)O_(7)^(2-),+14H^(+)+6I^(-),to, 2Cr^(3+)+3I_(2)+7H_(2)O)` (ii) Ferrous salts are oxidised to ferric salts:
`6Fe^(2+)+Cr_(2)O_(7)^(2-)+14H^(+) to 6Fe^(3+)+2Cr^(3+)+7H_(2)O`
(iii) `H_(2)S "is oxidised to sulphur"`:
`Cr_(2)O_(7)^(2-)+3H_(2)S+8H^(+)to2Cr^(3+)+7H_(2)O+3S`