[ggankinboon]

Initially, I add a small piece of vanadium into a 2M of Nitric acid. I heated it and the outcome is a pretty green colour. I predicted the presence of V3+ ion. And I wanted to collect the solution so I neutralized it with Sodium Carbonate. Initially, bubbling and a deep green colour. After shaking, I got it green again. I added more Sodium Carbonate and it does not turn back green. It shows a very very very dark green (close to black). I waited for a few days and nothing changed. So I decided to put a piece of more electropositive metal, and today I have a piece of Manganese metal. I put the metal inside the solution and shaked. The solution turns to light green (not as pretty as before). I do expect it to become lilac V2+ ion but it did not. After shaking for minutes, I got a yellow green solution and now a cloudy yellow. It is a suspension. Now, the solution becomes clearer and I can see tiny yellow particle down the bottle. Can anyone tells me what happened? Or any prediction Plssssss?

[Enthalpy]

Nitric acid often acts as an oxidizer, not an acid.
V²⁺ isn't the only possible product... Hydroxides?
If Mn has reacted, it can have produced coloured ions.