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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: sn1sn2e1e2 on March 20, 2014, 10:44:31 AM

Title: Reaction question
Post by: sn1sn2e1e2 on March 20, 2014, 10:44:31 AM

Quick question:
Which 2.00 M solution can be used to separate Al3+ from Fe3+ in an aqueous solution?

(A) HCl
(B) H2SO4
(C)NaCl
(D)NaOH

If you choose D, you are right, but I thought OH- ions always forms solids with Al3+ and Fe3+. If you add in OH ions, wouldn't both precipitate? Or do you need to precipitate both to "separate" them?

Title: Re: Reaction question
Post by: Hunter2 on March 20, 2014, 11:51:10 AM

Aluminium creates first precipitate as you described, but in excess of OH^- you will get complex like [Al(OH)₄]^-. Iron stands with its hydroxide.