Chemistry challenge.?

Question

This blue crystaline solid ---> dissolve in water and add dilute nitric acid and barium nitrate solution ---> a white precipitate "M".
This blue crystaline solid ---> dissolve in water & warm with NaOH solution ---> a gas "N", that turns red litmus blue.
This blue crystaline solid ---> dissolve in water & warm with NaOH solution ---> a blue precipitate, "O".
This blue precipitate, "O" is mixed with excess dilute sulphuric acid to give a blue aqueous solution that evaporates slowly to give a blue crystals, "P".

Q: What is the identity of substance "M", "N", "O" & "P"?

Solve this question correct with detailed workings and earn points!!! :)

Answer 1

M =Barium chloride (BaCl2). the blue crystalline solid is copper(II) chloride and when its mixed with barium nitrate and insoluble white precipitate barium chloride is formed.

N= Ammonia. I would agree.

O=Copper hydroxide[Cu(OH)2]. When copper(II) chloride is dissolved in water, the copper ions are in solution. When you raise the pH of of most metal salts above 9 or 10, you will precipitate out the metal hydroxide, hence copper hydroxide.

P=Copper sulfate dihydrate
If you look at the balanced equation:
Cu(OH)2+H2SO4>>CuSO4+2H20

Answer 2

M = barium sulphate (test for sulphate ion - look it up)
N = ammonia (only common alkaline gas - look it up)
O = copper hydroxide (test for Cu2+ - look it up). NB the ammonia will have been driven off by now.
P = hydrated copper sulphate crystals CuSO4.5H2O. The CuSO4 was formed by a neutralisation reaction.

I'm sure that you can now work out the equations for yourself.

Answer 3

M= anhydrous barium nitrate
N= CO2 ( or any other alkaline gas)
O= what's your blue crystal made of?
P= ?