InterviewSolution
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InterviewSolution
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In which of the following properties does white phosphorus resemble red phosphorus?A. Reaction with hot `NaOH` soln.B. PhosphorescenceC. Solubitlity in organic solventsD. Burning of air |
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Answer» Correct Answer - 4 Both white and red burn in excess of oxygen to from tetraphosphorus decaoxide: `P_(4)(s)+5O_(2)(g) rarr P_(4)O_(10)(s)` White `P` ignites in air at `35^(@)C` while red `P` ignites in air at `260^(@)C`. White `P`, has much lower melting and boiling points than red `P` , because very litter energy is required to sever the weak dispersion forces between the individual `P_(4)` molecules in the former allotrope. Similary white `P` , unlike red `P` , is easily dispersed as in carbon disulphide, butthis solvent is ineffecuture in breaking down the strong macromolecular structure of red `P`. White `P` is less dence than the red variety because its structure is less compact. The more open structure of the white from also accounts for its high chemical reactivity, which is further enhanced by the fact that considerable strain is present in the `P_(4)` units which is relieved by chemical reactions. While `P` dissolves in boiling `NaOH` solution in an inert atmosphere giving `PH_(3)` `P_(4)+3NaOH+3H_(2)O rarr PH_(3)+3NaH_(2)PO_(2)` Red `P` shows no sign of reaction ,White `P` glows in dark (chemilluminescemce or phosphorescence) due to slow combustion while red `P` does not glow. |
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