Silver Halides

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Isabelle Fontanilla 1I
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Joined: Fri Sep 28, 2018 12:19 am

Silver Halides

Postby Isabelle Fontanilla 1I » Sun Nov 11, 2018 8:19 pm

Why is the solubility among the silver halides (from AgF to AgI) decreasing(less soluble) as the size of the anion gets bigger? I thought that increasing the size of the components of a compound increases the compound's solubility(more soluble) because the bond holding it together gets weaker due to increased distance?

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Re: Silver Halides

Postby Chem_Mod » Sun Nov 11, 2018 8:24 pm

The bond does get stronger, but think about how molecules with more ionic character behave in water, eg. ionic compound NaCl. Molecules with more ionic character tend to dissolve in water easier.

Atul Saha 3D
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Joined: Fri Sep 28, 2018 12:25 am

Re: Silver Halides

Postby Atul Saha 3D » Sun Nov 11, 2018 8:29 pm

Silver Halides (except for AgF) have a very high lattice energy. We didn't cover this in class, but basically the energy of the bonds holding the structure of the silver halides together is too much to overcome, hence they are insoluble.

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Esha Harwalkar 3F
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Joined: Fri Sep 28, 2018 12:26 am

Re: Silver Halides

Postby Esha Harwalkar 3F » Sun Nov 11, 2018 8:33 pm

Per what I understand, the bigger the anion is, the more polarizable it is. This happens because larger anions have larger electron clouds that are easier to distort, giving them higher polarizability. This trait also means the larger anion will have more covalent character, because there is greater electrostatic attraction on the electron surrounding the anion, and it wants to share the electrons more with the cation. Increasing covalent character also leads to decreasing solubility, because covalent bonds mean there is higher dissociation energy (than ionic bonds), which makes it harder to break apart (i.e. in water)

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