7.71 What is the maximum concentration of equimolar solutions of ferrous sulphate and sodium sulphide so that when mixed in equal volumes, there is no precipitation of iron sulphide? (For iron sulphide, Ksp = 6.3 × 10-18).
The solubility product of the
Equals number of moles of ferrous sulphate and sodium sulphide are mixed in an equal volume.
Let be the concentration of ferrous sulphate and sodium sulphide. On mixing the equimolar solution, the volume of the concentration becomes half.
The ionisation of ferrous sulphide;
Therefore, for no precipitation, ionic product = solubility product
By solving the above equation, we get
The maximum concentration of both the solution is M