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Why is white phosphorus soluble in $\ce{CS2}$ but red phosphorus not? Is it something in relation with the structures of both? Please explain.

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  • $\begingroup$ You can (and should!) use the \ce{...} environment to format chemical equations and formulae; see here for a basic intro and here for a complete documentation. P/S names of chemicals are not capitalised. $\endgroup$ – orthocresol Feb 23 '17 at 13:42
  • $\begingroup$ What do you know about white phosphorus, to begin with? $\endgroup$ – Ivan Neretin Feb 23 '17 at 13:42
  • $\begingroup$ @IvanNeretin That white phosphorus is tetrahedral closed ${P_4}$ molecule and red phosphorus is kind of open structure formed from ${P_4}$ molecule. $\endgroup$ – Piyush Raut Feb 23 '17 at 13:45
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    $\begingroup$ That's it, then. To dissolve red phosphorus, you'd have to break covalent bonds, which is hard. Dissolving white phosphorus is much easier. $\endgroup$ – Ivan Neretin Feb 23 '17 at 13:50
  • $\begingroup$ @IvanNeretin Then what kind of bonds are in $P_4$ molecule in white phosphorus among $P-P$ atoms aren't the covalent ?Do we need to break $P-P$ bonds Or the interactions between two $P_4$ molecules while considering solubility? $\endgroup$ – Piyush Raut Feb 23 '17 at 13:59
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White phosphorus has P4 molecules packed into a crystal,these dissolve readily in Carbon Disulfide.

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Whereas Red phosphorus is polymeric in nature. It is a derivative of white phosphorus where one P-P bond is broken and an addtional bond is formed with neighboring tetrahedron molecule resulting in a chain like structure .

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Like all long chain polymers this will lower its ability to dissolve and its solubility in solvents

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