Metal and sodium hydroxide.

[Primarygun]

Several questions related to alkalis.

1.Are all reactions between metal compounds and alkalis, and between metal compounds and acid displacement reactions? I think this is quite important as it helps very much to predict the product of these reactions.

2.Ammonia solution added into solution of metal salt always gives out ammonia?

3.Calcium hydroxide formed when sodium hydroxide added to a solution of calcium nitrates. Is the result(forming hydroxide) the same if calcium, magnesium are put in? Or even hydrogencarbonates of these metals.

4.adding excess ammonia can turn solution of hydroxide(precipitate) into some complex ions. Why the series do not follow the reactivity series?

Hydroxide of calcium, magnesium, lead cannot redissolve again while zinc hydroxide can, why?

Thanks for any responses.

[budullewraagh]

1. i would imagine under reasonable conditions yes. under some abstract conditions, not necessarily

2. i don't think so

3. if you add calcium to a solution of calcium nitrate, you keep your calcium nitrate and you get calcium hydroxide. if you add magnesium you get magnesium hydroxide and calcium nitrate. if you add the bicarbonate of calcium you get calcium nitrate and calcium bicarbonate. if you add the bicarbonate of magnesium you get calcium nitrate and magnesium bicarbonate

4. this question is poorly worded... could you rephrase with a little more information?

[Primarygun]

Ok. Zinc hydroxide precipitate redissolve in excess ammonia solution while lead, potassium do not, why?

[YT2095]

are you refering to the Amine Ligand?

[fermions]

I think that's what s/he means... anyway I want to add a question related to that.. copper hydroxide is insoluble in excess NaOH (or alkaline) but when ammonia solution is added to it... it forms tetramminecopper(II) complex ion and dissolves... so why doesn't it become Cu(OH)4 and dissolved in excess Naoh also...

and my teacher says the reaction between NH4+and OH- are not reversible because strong base displace weak base and it can't go the other way round... I don't quite believe in my teacher... so when is this displacement rule applicable?

thanks

[budullewraagh]

so why doesn't it become Cu(OH)4 and dissolved in excess Naoh also...

because the tetraamine copper complex doesnt involve NH4OH. in fact, NH4OH isnt aqueous ammonia. instead it's NH3. the tetraamine copper complex is quite an interesting structure actually. the cupric cation just sorta sits in the middle while the nitrogen, being trivalent with a lone pair, use that lone pair to form coordinate covalent bonds with the cupric cation. the hydroxide is outside of all that

[Primarygun]

NH4OH isnt aqueous ammonia. instead it's NH3

Some ammonia gases are trapped and stay as gas between water molecules and some decompose?

[budullewraagh]

no, they just all stay as NH3(aq) between water molecules

[Primarygun]

Why does a hydroxide ion from ammonia solution displaces or be displaced by the anion of the metal compound put in the solution?