[kemikalman]

Hi, I´ve been trying to prepare nickel sulfate by direct reaction of elemental nickel and sulfuric acid in the range of concentration from 40% to 60%; acording to what I´d read and investigated, this reaction proceeds succesfuly.

I made a test with high quality nickel powder and sulfuric acid, both from Merck, and everything was fine, beautyfull green crystals were obtained, but then I made the same reaction using commercial electrolitic nickel form Canada and commercial sulfuric acid from local plants,  and nickel seemed not to dissolve yielding a green-yellow insoluble powder and sulfurous gases and nothing of nickel sulfate, the reaction was completely different to what I have obtained before. Then I tried the reaction with the same canadian commercial nickel and Merck sulfuric acid, and again the reaction was a mess, it seems like sulfuric acid was reduced to sulfur by nickel,

Do anybody has any information about this reaction?

[two39plutonium]

Seems to be a simple redox reaction to me.  Gotta get from Ni zero to Ni (II) somehow and the only thing around is sulfate, check the latimer diagrams.  All you did was dissolve the oxide powder since it was already oxidized, no redox.

[AgG]

I haven't checked the potential series for Ni and H2 so I will assume you are correct that H+ can oxidize Ni(0). My question then would be whether or not the Ni from canada was finely divided.

[AgG]

actually, I didnt read the last part of your post there... interesting.  What is the literature prep?