Contact process, V2O5 used as a catalyst, reacts to form vanadium (iv) oxide, is this V2O4 or VO2? I've seen it put both ways, which one is correct(rather, which one will get me the marks in the exam)?
SO2 + V2O5 → SO3 + 2VO2
2VO2 +½O2 → V2O5
or
SO2 + V2O5 → SO3 + V2O4
V2O4 + ½O2 → V2O5
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Oh, does anyone happen to have a definitive list of metal aqua-ion colours and the colours when you add OH- etc. One moment [Cr(H2O)6]3+ is violet, then I have my teacher telling me it's green, the test tube in front of me telling me it's closer to black than anything else. >.> Driving me mad and it's only a trivial bit of memorising a few colours but I don't know which colours to remember. Again, I don't care if it's actually red, if saying it's blue get's me the mark in the exam that's what counts. :>