[Kneelo]

Hi
If I mix Cr2(SO4)3 + NaOH a precipitate is formed , but I'm not sure which ! Is it Cr2OH or Na(SO4)3 any sugestions would be appreciated .
Thanks Kneelo

[AWK]

Cr₂(SO₄)₃ + 6NaOH = 2 Cr(OH)₃(s) + 3Na₂SO₄

[jdurg]

If memory serves me correctly, all alkali metal salts are soluble.  

[AWK]

If memory serves me correctly, all alkali metal salts are soluble.  
 It depends on anion. KClO₄, K₂[PtCl₆ ], K₂Na[Co(NO₂)₆ ] are poor soluble, Na[Sb(OH)₆ ], Li₂CO₃,
Rb₂Na[Co(NO₂)₆ ], Cs₂Na[Co(NO₂)₆ ] also. Poor solubility means in this case less than 1g/L, sometimes a few mg/L.

[hmx9123]

Remember, everything is soluble, the question is how soluble.  Even things that you normally think of as incredibly soluble, like sodium chloride and sodium sulfate, can precipitate under the right conditions.  I have actually run a reaction before in which I had sodium sulfate precipitate out on me.  For a good look at inorganic solubilities, try the CRC handbook of chemistry and physics; the older editions contain inorganic compound solubility constants.  Lange's Handbook of chemistry also gives a lot of constants, but many are given as equilibrium constants.