Primarygun Posted January 26, 2005 Share Posted January 26, 2005 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. Link to comment Share on other sites More sharing options...
budullewraagh Posted January 26, 2005 Share Posted January 26, 2005 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? Link to comment Share on other sites More sharing options...
Primarygun Posted January 27, 2005 Author Share Posted January 27, 2005 Ok. Zinc hydroxide precipitate redissolve in excess ammonia solution while lead, potassium do not, why? Link to comment Share on other sites More sharing options...
YT2095 Posted January 27, 2005 Share Posted January 27, 2005 are you refering to the Amine Ligand? Link to comment Share on other sites More sharing options...
fermions Posted January 27, 2005 Share Posted January 27, 2005 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 Link to comment Share on other sites More sharing options...
budullewraagh Posted January 27, 2005 Share Posted January 27, 2005 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 Link to comment Share on other sites More sharing options...
Primarygun Posted January 28, 2005 Author Share Posted January 28, 2005 NH4OH isnt aqueous ammonia. instead it's NH3 Some ammonia gases are trapped and stay as gas between water molecules and some decompose? Link to comment Share on other sites More sharing options...
budullewraagh Posted January 28, 2005 Share Posted January 28, 2005 no, they just all stay as NH3(aq) between water molecules Link to comment Share on other sites More sharing options...
Primarygun Posted January 29, 2005 Author Share Posted January 29, 2005 Why does a hydroxide ion from ammonia solution displaces or be displaced by the anion of the metal compound put in the solution? Link to comment Share on other sites More sharing options...
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