My daughter has a chemistry exam on Tuesday. She is doing quite well with her revision except for the following table which she is having difficulty remembering.

Does anyone know of an easy way to remember this? Or perhaps if someone could explain why these exceptions are insoluble that will help her instead? Insoluble salts

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    $\begingroup$ This would appear to be for an introductory general chemistry class. If that's the case, it's quite likely that the explanations for why these solubility trends are observed will be confusing, since they really require at least qualitative understanding of more advanced concepts (thermodynamics, physical chemistry, etc.). Unfortunately, chemistry at a basic level usually comprises a lot of memorization without proper motivation for same. $\endgroup$ – Greg E. Jun 8 '14 at 22:56
  • $\begingroup$ As a mnemonic strategy, I would advise trying to find some associations, use grouping, and prioritize. Notice, for example, that sodium and potassium are both alkali metals, group IA (that is, they're grouped in the same column on the periodic table). Barium and calcium are both alkali earth metals, group IIA. Notice also that the exceptions to the rule of insolubility of carbonates and hydroxides overlap with rule #1 (i.e., if rule #1 is simply given priority, the exceptions to rule #5 need not be explicitly memorized as such). $\endgroup$ – Greg E. Jun 8 '14 at 23:14
  • $\begingroup$ Greg, she's a clever girl and remembers things much better if she knows the reason for it, simple memorisation doesn't work well for her at all. $\endgroup$ – Peter Morris Jun 9 '14 at 7:53
  • $\begingroup$ @PeterMorris If it helps, Barium Sulphate is given as a 'meal' to patients about to undergo an X Ray of their gut as the Ba2SO4 is more likely to absorb the X Rays and hence allow the gut to show up on the X Ray... Since it is toxic it is important that it is not soluble i.e. does not break up into ions and get absorbed by the body. Perhaps the use of other such examples could help ? $\endgroup$ – Ari Ben Canaan Jun 9 '14 at 15:59
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    $\begingroup$ Ammonium hydroxide listed among the salts. That hurts. $\endgroup$ – Abel Friedman Oct 12 '14 at 18:23

Understanding why it happens unfortunately will not help her to remember. This is the classic case where you have to find a dirty way to remember them. Maybe you can make some practical experiment I remember most of them with a practical application of the salts.

There are a lot of online resource regarding Mnemonic Tricks to remember solubility rules, these are two video on youtubes.

Memonic tricks


Quoting the song:

This is solubility it's so crazy, don't be a fool and follow these rules!


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