ROadmanKys
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how would i know what the reactants were and under what chapter in aqa would i refer to?
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username3718068
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(Original post by ROadmanKys)
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how would i know what the reactants were and under what chapter in aqa would i refer to?
Q:
you get a pale cream precipitate when you add acdified silver nitrate solution.
Which anion is responsible for this cream colour in the silver halide?

You get a white ppt when you add NaOH which remains insoluble. Hence this can be calium hydroxide or magnesium hydroxide.
Refer to solubility of hydroxide/sulphate going down grp 2 AS chem

R:
white ppt when you add acidified silver nitrate solution. This halide which gives the white colour is _______
white ppt which redissolves in XS. This cation is Al

S:
you white preciptate when u added acidified BaCl2. This is a positive test for sulphate anion
u got a brwn ppt when u added NaOH and u got bubbles of CO2 when u added sodium carbonate.
Hence u have a cation in the +3 oxidation state
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ROadmanKys
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(Original post by dip0)
Q:
you get a pale cream precipitate when you add acdified silver nitrate solution.
Which anion is responsible for this cream colour in the silver halide?

You get a white ppt when you add NaOH which remains insoluble. Hence this can be calium hydroxide or magnesium hydroxide.
Refer to solubility of hydroxide/sulphate going down grp 2 AS chem

R:
white ppt when you add acidified silver nitrate solution. This halide which gives the white colour is _______
white ppt which redissolves in XS. This cation is Al

S:
you white preciptate when u added acidified BaCl2. This is a positive test for sulphate anion
u got a brwn ppt when u added NaOH and u got bubbles of CO2 when u added sodium carbonate.
Hence u have a cation in the +3 oxidation state
I cant find anywhere for test of Aluminium in these solutions and how can you decipher that it was calcium and not magnesium as the solubility of hydroxides increases down the group. is it because with HCL , there was no observation, therfore it couldnt be Mg, and Ca(OH)2 (aq) + CO2 (g)  CaCO3 (s) + H2O(l) forms a carbonate which tests positive with the na2co3 solution?
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username3718068
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(Original post by ROadmanKys)
I cant find anywhere for test of Aluminium in these solutions and how can you decipher that it was calcium and not magnesium as the solubility of hydroxides increases down the group. is it because with HCL , there was no observation, therfore it couldnt be Mg, and Ca(OH)2 (aq) + CO2 (g)  CaCO3 (s) + H2O(l) forms a carbonate which tests positive with the na2co3 solution?
1. look at reaction of transition metal ions in aquesous solutions chapter.

2. solubility increases going down the group. Since Ca and Mg are at the top of grp 2, then their hydroxides are least soluble compared to the other grp 2 cations.
So they both exist as white ppt.
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ROadmanKys
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(Original post by dip0)
1. look at reaction of transition metal ions in aquesous solutions chapter.

2. solubility increases going down the group. Since Ca and Mg are at the top of grp 2, then their hydroxides are least soluble compared to the other grp 2 cations.
So they both exist as white ppt.
Ahh i see, thanks
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