what reagent with observations are used to separate(i)Fe2+$Fe3+ (ii)Mg2+$Fe2+ (iii)Cu2+$Al3+ (iv)SO4(2+)$CO3(2+)
To separate the different ions, we typically use reagents that will selectively react with one ion while not affecting the other ions. Here are the reagents and observations for separating the given ions:
(i) Fe2+ and Fe3+:
To separate Fe2+ and Fe3+, we can use potassium hexacyanoferrate(II) [K4Fe(CN)6] which forms a deep blue precipitate called Prussian blue (Fe4[Fe(CN)6]3).
Observation: A deep blue precipitate indicates the presence of Fe2+.
(ii) Mg2+ and Fe2+:
To separate Mg2+ and Fe2+, we can use sodium hydroxide (NaOH). Magnesium hydroxide [Mg(OH)2] is a white precipitate that forms when NaOH is added to a solution containing Mg2+. Adding NaOH to a solution containing Fe2+ does not result in a precipitate.
Observation: A white precipitate indicates the presence of Mg2+.
(iii) Cu2+ and Al3+:
To separate Cu2+ and Al3+, we can use sodium hydroxide (NaOH). Copper hydroxide [Cu(OH)2] is a blue precipitate that forms when NaOH is added to a solution containing Cu2+. Adding NaOH to a solution containing Al3+ does not result in a precipitate.
Observation: A blue precipitate indicates the presence of Cu2+.
(iv) SO4(2-) and CO3(2-):
To separate SO4(2-) and CO3(2-), we can use barium chloride (BaCl2). Barium sulfate [BaSO4] is a white precipitate that forms when BaCl2 is added to a solution containing SO4(2-). On the other hand, adding BaCl2 to a solution containing CO3(2-) does not result in a precipitate.
Observation: A white precipitate indicates the presence of SO4(2-).
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