Question

I need help to develop a schemes flowchart to separate Al3+, fe3+, Ni2+, Pb2+ using the following reagents HCl, NH3 and NaOH. Three steps are needed to achieve a separation of the four cations from eath use of the reagents (HCl, NH3, or NaOH in each step). Separate Pb2+ first

Answer 1

Answer on Question #57996, Chemistry / General Chemistry

I need help to develop a schemes flowchart to separate Al3+, fe3+, Ni2+, Pb2+ using the following reagents HCl, NH3 and NaOH. Three steps are needed to achieve a separation of the four cations from each use of the reagents (HCl, NH3, or NaOH in each step). Separate Pb2+ first

**Solution:**

1) Add to the HCl solution to a strongly acidic medium.

Pb²⁺ by reacting c HCl forms a precipitate PbCl₂:

$$\mathrm{Pb}^{2+} + \mathrm{Cl}^- \rightarrow \mathrm{PbCl}_2\downarrow$$

while remaining cations remain in solution.

2) To a solution after separation of precipitate PbCl₂ add NH₃ solution until the characteristic smell .. Moreover, all three form a cation precipitation:

$$\mathrm{Fe}^{3+} + 3\mathrm{NH}_3\cdot\mathrm{H}_2\mathrm{O} \rightarrow \mathrm{Fe(OH)}_3\downarrow + 3\mathrm{NH}_4^+$$ $$\mathrm{Al}^{3+} + 3\mathrm{NH}_3\cdot\mathrm{H}_2\mathrm{O} \rightarrow \mathrm{Al(OH)}_3\downarrow + 3\mathrm{NH}_4^+$$ $$\mathrm{NiCl}_2 + \mathrm{NH}_3 \cdot \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{NiOHCl} + \mathrm{NH}_4^+ \mathrm{Cl}$$

A lot of solution of ammonia nickel will be dissolved.

3) To the precipitate of hydroxides of iron and aluminum to add NaOH solution. Thus aluminum will go into solution:

$$\mathrm{Al(OH)}_3 + 3\mathrm{OH}^- \rightarrow [\mathrm{Al(OH)}_6]^{3-}$$