Explain the molecular structure and properties of phosphorus pentachloride $(PCl_5)$.
(N/A) Structure: Phosphorus pentachloride $(PCl_5)$ has a trigonal bipyramidal geometry in gaseous and liquid phases. The phosphorus atom undergoes $sp^3d$ hybridization.
In $PCl_5$,the three equatorial $P-Cl$ bonds are equivalent,while the two axial $P-Cl$ bonds are longer than the equatorial bonds. This is because the axial bond pairs experience greater repulsion from the equatorial bond pairs compared to the repulsion between equatorial bond pairs themselves.
Properties of $PCl_5$:
$1$. $PCl_5$ is a yellowish-white powder. In moist air,it hydrolyzes to give phosphorus oxychloride $(POCl_3)$ and finally phosphoric acid $(H_3PO_4)$:
$PCl_5 + H_2O \rightarrow POCl_3 + 2HCl$
$POCl_3 + 3H_2O \rightarrow H_3PO_4 + 3HCl$
$2$. When heated,it sublimes,but on strong heating,it decomposes:
$PCl_5 \xrightarrow{\Delta} PCl_3 + Cl_2$
$3$. It reacts with organic compounds containing the $-OH$ group,converting them into chloro derivatives:
$C_2H_5OH + PCl_5 \rightarrow C_2H_5Cl + POCl_3 + HCl$
$CH_3COOH + PCl_5 \rightarrow CH_3COCl + POCl_3 + HCl$
$4$. Finely divided metals,upon heating with $PCl_5$,yield their corresponding chlorides:
$2Ag + PCl_5 \rightarrow 2AgCl + PCl_3$
$Sn + 2PCl_5 \rightarrow SnCl_4 + 2PCl_3$
In $PCl_5$,the three equatorial $P-Cl$ bonds are equivalent,while the two axial $P-Cl$ bonds are longer than the equatorial bonds. This is because the axial bond pairs experience greater repulsion from the equatorial bond pairs compared to the repulsion between equatorial bond pairs themselves.
Properties of $PCl_5$:
$1$. $PCl_5$ is a yellowish-white powder. In moist air,it hydrolyzes to give phosphorus oxychloride $(POCl_3)$ and finally phosphoric acid $(H_3PO_4)$:
$PCl_5 + H_2O \rightarrow POCl_3 + 2HCl$
$POCl_3 + 3H_2O \rightarrow H_3PO_4 + 3HCl$
$2$. When heated,it sublimes,but on strong heating,it decomposes:
$PCl_5 \xrightarrow{\Delta} PCl_3 + Cl_2$
$3$. It reacts with organic compounds containing the $-OH$ group,converting them into chloro derivatives:
$C_2H_5OH + PCl_5 \rightarrow C_2H_5Cl + POCl_3 + HCl$
$CH_3COOH + PCl_5 \rightarrow CH_3COCl + POCl_3 + HCl$
$4$. Finely divided metals,upon heating with $PCl_5$,yield their corresponding chlorides:
$2Ag + PCl_5 \rightarrow 2AgCl + PCl_3$
$Sn + 2PCl_5 \rightarrow SnCl_4 + 2PCl_3$
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Similar Questions
There are some deposits of nitrates and phosphates in earth's crust. Nitrates are more soluble in water. Nitrates are difficult to reduce under the laboratory conditions but microbes do it easily. Ammonia forms a large number of complexes with transition metal ions. Hybridization easily explains the ease of sigma donation capability of $NH_3$ and $PH_3$. Phosphine is a flammable gas and is prepared from white phosphorus.
$1.$ Among the following,the correct statement is:
$(A)$ Phosphates have no biological significance in humans
$(B)$ Between nitrates and phosphates,phosphates are less abundant in earth's crust
$(C)$ Between nitrates and phosphates,nitrates are less abundant in earth's crust
$(D)$ Oxidation of nitrates is possible in soil
$2.$ Among the following,the correct statement is:
$(A)$ Between $NH_3$ and $PH_3, NH_3$ is a better electron donor because the lone pair of electrons occupies a spherical '$s$' orbital and is less directional
$(B)$ Between $NH_3$ and $PH_3, PH_3$ is a better electron donor because the lone pair of electrons occupies an $sp^3$ orbital and is more directional
$(C)$ Between $NH_3$ and $PH_3, NH_3$ is a better electron donor because the lone pair of electrons occupies an $sp^3$ orbital and is more directional
$(D)$ Between $NH_3$ and $PH_3, PH_3$ is a better electron donor because the lone pair of electrons occupies a spherical '$s$' orbital and is less directional
$3.$ White phosphorus on reaction with $NaOH$ gives $PH_3$ as one of the products. This is a:
$(A)$ dimerization reaction
$(B)$ disproportionation reaction
$(C)$ condensation reaction
$(D)$ precipitation reaction
Give the answer for questions $1, 2$ and $3.$
$1.$ Among the following,the correct statement is:
$(A)$ Phosphates have no biological significance in humans
$(B)$ Between nitrates and phosphates,phosphates are less abundant in earth's crust
$(C)$ Between nitrates and phosphates,nitrates are less abundant in earth's crust
$(D)$ Oxidation of nitrates is possible in soil
$2.$ Among the following,the correct statement is:
$(A)$ Between $NH_3$ and $PH_3, NH_3$ is a better electron donor because the lone pair of electrons occupies a spherical '$s$' orbital and is less directional
$(B)$ Between $NH_3$ and $PH_3, PH_3$ is a better electron donor because the lone pair of electrons occupies an $sp^3$ orbital and is more directional
$(C)$ Between $NH_3$ and $PH_3, NH_3$ is a better electron donor because the lone pair of electrons occupies an $sp^3$ orbital and is more directional
$(D)$ Between $NH_3$ and $PH_3, PH_3$ is a better electron donor because the lone pair of electrons occupies a spherical '$s$' orbital and is less directional
$3.$ White phosphorus on reaction with $NaOH$ gives $PH_3$ as one of the products. This is a:
$(A)$ dimerization reaction
$(B)$ disproportionation reaction
$(C)$ condensation reaction
$(D)$ precipitation reaction
Give the answer for questions $1, 2$ and $3.$
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