Question

solution is prepared by adding 18 mL of 0.200 M Fe(NO3)3and 2 mL of 0.0020 M KSCN. Calculate the initial concentrations of Fe3 and SCN-in the solution

Answer 1

Answer : The initial concentration of
`Fe^(3+)` and
`SCN^-` in the solution are, 0.200 M and 0.0020 M respectively.

Explanation : Given,

Concentration of
`Fe(NO_3)_3` = 0.200 M

Concentration of
`KSCN` = 0.0020 M

As, 1 mole of
`Fe(NO_3)_3` dissociate then it gives 1 mole of
`Fe^(3+)` ion and 3 moles of
`NO_3^-` ion.

So, 0.200 M of
`Fe(NO_3)_3` dissociate then it gives 0.200 M of
`Fe^(3+)` ion and (3×0.200 M) of
`NO_3^-` ion.

and,

As, 1 mole of
`KSCN` dissociate then it gives 1 mole of
`K^(+)` ion and 1 mole of
`SCN^-` ion.

So, 0.0020 M of
`KSCN` dissociate then it gives 0.0020 M of
`K^(+)` ion and 0.0020 M of
`SCN^-` ion.

Thus, the initial concentration of
`Fe^(3+)` and
`SCN^-` in the solution are, 0.200 M and 0.0020 M respectively.