Sciencemadness Discussion Board

Nickel(II) something-nate sludge

crystal grower - 18-5-2018 at 08:35

I needed to make some Ni(NO3)2 so I reacted HNO3 with Ni (Nickel was in a slight excess). Beside green solution I got this weird precipitate after filtration. I have no idea what it is. (The solution is dilute enough to Dissolve all the salt).
Can anyone help?


IMG_20180518_132615.jpg - 1.6MB IMG_20180518_132557.jpg - 1.6MB

[Edited on 18-5-2018 by crystal grower]

DraconicAcid - 18-5-2018 at 08:58

Looks like nickel(II) hydroxide from not adding enough acid?

crystal grower - 18-5-2018 at 09:05

It looks like that. I did not realize it will form hydroxide, I thought excess Ni will simply stay unreacted. I'll try adding more HNO3

LearnedAmateur - 18-5-2018 at 10:39

How could a nickel hydroxide ppt. form without some sort of base in those quantities? I thought you would need at least a small amount of ammonia or alkali hydroxide to do so. Haven’t really had a play around with nickel compounds so I’m curious.

DraconicAcid - 18-5-2018 at 10:52

I'd guess Ni(II) hydrolyzes to give nickel hydroxide and hydronium ion, and the hydronium ion reacts with more nickel to give Ni(II) and hydrogen.

fusso - 22-5-2018 at 17:21

Quote: Originally posted by DraconicAcid  
I'd guess Ni(II) hydrolyzes to give nickel hydroxide and hydronium ion, and the hydronium ion reacts with more nickel to give Ni(II) and hydrogen.

Shouldn't Ni reduce HNO3 to NOx instead of H2?

DraconicAcid - 22-5-2018 at 17:28

Quote: Originally posted by fusso  
Quote: Originally posted by DraconicAcid  
I'd guess Ni(II) hydrolyzes to give nickel hydroxide and hydronium ion, and the hydronium ion reacts with more nickel to give Ni(II) and hydrogen.

Shouldn't Ni reduce HNO3 to NOx instead of H2?


Depends on how much nitrate ion is left in solution.