Compounds of Phosphorus - PCl5

Q: Identify the incorrect statement related to \$PCl_5\$ from the following:

(1) True(2) True(3) True(4) False Due to longer and hence weaker axial bonds, \$PCl_5 \$ is a reactive molecule.

Q: Acetic acid reacts with \$ PCl_5\$ to form :

Acetic acid reacts with \$PCl_5\$ to form acetyl chloride.\$ \underset {\text{acetic acid}}{CH_3 COOH + PCl_5} \rightarrow \underset { \text {acetyl chloride} } {CH_3 COCl} + POCl_3 + HCl \$

Q: In solid state \$PCl_{5}\$ is a :

In solid state \$PCl_5\$ tries to exist as oppositely charged ions like (1) \$PCl_4^{+}\$ and (2) \$PCl_6^{-}\$ as the ionic bonding enhances the crystalline nature . also \$PCl_4^{+}\$ is tetrahedral , while \$PCl_6^{-}\$ is octahedral . these structure fit well into each other which gives more stability to solid structure .Hence option D is correct.

Q: In solid state \$PCl_{5}\$ exist as an ionic solid \$[PCl_{4}]^{+} [PCl_{6}]^{-}\$ hybridisation state of cation and anion respectively :

In the solid state it exists as an ionic solid, \${[PCl4]}^{+}{[PCl6]}^{-}\$. The cation, \${[PCl4]}^{+}\$ is tetrahedral and \${sp}^{3}\$ hybridised. The anion, \${[PCl6]}^{-}\$ is octahedral and is \${sp}^{3}{d}^{2}\$ hybridised.

Q: Among the following the number of compounds that can react with \$PCl_{5}\$ to give \$POCl_{3}\$ is :\$O_{2},CO_{2},SO_{2},H_{2}O,H_{2}SO_{4},P_{4}O_{10}\$

Except for \$O_2\$ and \$CO_2\$ all others react with \$PCl_5\$ to give \$POCl_3\$.\$SO_2(g)+PCl_5(s)\rightarrow SOCl_2(l)+POCl_3(l)\$\$PCl_5+H_2O\rightarrow POCl_3+2HCl\$\$H_2SO_4+2PCl_5\rightarrow 2POCl_3+SO_2Cl_2+HCl\$\$P_4O_10+6PCl5\rightarrow 10POCl_3\$So there 4 compounds which can react with \$PCl_5\$.Hence option C is correct.

Q: What happens when \$PCl_5\$ is heated?

When \$PCl_5\$ is heated it decomposes to give \$PCl_3\$ & chlorine gas. An equilibrium is established.\${PCl_5}_{(g)} \rightleftharpoons {PCl_3}_{(g)}+{Cl_2}_{(g)}\$

Q: Draw structure and write geometry of \$PCl_3\$ and \$PCl_5\$.

\$PCl_3\$ have pyramidal geometry , where as \$PCl_5\$ have trigonal bipyramidal shape.

Q: In the solid state \$PCl_{5}\$ exists as:

In the solid state, \$PCl_5\$ prefers to exist as oppositely charged ion like \$[PCl_4]^+\$ and \$[PCl_6]^-\$ as ionic bonding enhances the crystalline nature. The shape is more stable in the ionic form as it forms the tetrahedral and octahedral shape.

Q: Answer the following:Why does \$PCl_3\$ fume in air?

\$PCl_3\$ combines with moisture of air and undergoes hydrolysis giving fumes of \$HCl\$.\$PCl_3+3H_2O \to H_3PO_3+3HCl\$

Q: Write down a balanced equation for the hydrolysis of \$PCl_{5}\$ with heavy water.

It reacts with heavy water to form phosphorus oxychloride \$(POCl_{3})\$ and deuterium chloride \$(DCl). POCl_{3}\$ reacts further with heavy water to form \$(DCl). POCl_{3}\$.\$PCl_{5} + D_{2}O \rightarrow POCl_{3} + 2DCl\$\$\underline {POCl_{3} + 3D_{2}O \rightarrow D_{3}PO_{4} + 3DCl}\$\$PCl_{5} + 4D_{2}O\rightarrow D_{3}PO_{4} + \underset {Deuterium\ chloride}{5DCl}\$