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The p-Block Elements

Short Answer Type

701.

How would you account for the following:
Interhalogen compounds are strong oxidising agents.

223 Views

702.

How would you account for the following:
Sulphur hexafluoride is less reactive than sulphur tetrafluoride.

318 Views

703.

How would you account for the following:
In the noble gases only xenon forms known chemical compounds.

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704. Compare the structural shapes of the following species: SF₆ and SF₄.

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705.

Write balanced chemical equations for the following reactions:
(a) ${Ca}_{3} P_{2} + H_{2} O \to$
(b) ${XeF}_{6} + 3 H_{2} O \to$

153 Views

Long Answer Type

706. Explain the following:
(i) Most of the known noble gas compounds are those of Xenon.
(ii) ClF₃exists but FCl₃ does not.
(iii) Among the hydrides of elements of Group 16, water shows unusual physical
properties.
(iv) Unlike phosphorus, nitrogen shows little tendency for catenation.
(v) Despite lower electron affinity, fluorine is a stronger oxidising agent than chlorine.

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707. Discuss the properties of oxygen, sulphur, selenium, tellurium and polonium (group 16 elements) with reference of following: (i) metallic (non-metallic character), (ii) catenation, (iii) thermal stability of hydrides, (iv) oxidation states (v) allotropy.

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708.

Describe the molecular shapes of the following: (i) SF₄, (ii) BrF₅, (iii) IF₃, (iv) PF₅, (v) XeF₂.

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709. Give reasons for:
(i) Ozone is more reactive than oxygen.
(ii) An acidified K₂Cr₂O₇ paper on being exposed to SO₂ turns green.
(iii) Sulphuric acid never acts as a reducing agent.
(iv) Noble gases are mostly chemically inert.
(v) Nitrogen is fairly inert.

(i) Ozone is a powerful oxidizing agent and oxidation with ozone evolves more heat and usually starts at a lower temperature than oxidation with oxygen. It reacts with non-saturated organic compounds to produce ozonides, which are unstable and may decompose with explosive violence. Ozone is an unstable gas which, at normal temperatures, decomposes to diatomic oxygen. At elevated temperatures and in the presence of certain catalysts such as hydrogen, iron, copper and chromium, this decomposition may be explosive.

ii) When SO₂ gas is passed through acidified potassium dicromate solution the orange colour potassium dichromate disappear and green colour ofchomium sulphate appears.

3SO₂ +K₂Cr₂O₇ +H₂SO₄ ----> K₂SO₄ +Cr₂(SO₄)_{3green colour} +H₂O

iii) The concentrated sulphuric acid can act both as an acid and as an oxidising agent. The concentrated sulphuric acid gives a hydrogen ion to the halide ion to produce a hydrogen halide. Because this is a gas, it immediately escapes from the system sulphuric acid ionises in two steps.

H₂SO₄(aq) + H₂O(l) → H₃O⁺(aq) + HSO₄^–(aq)
K_a1 = very large (K_a1 >10)

HSO₄^–(aq) + H₂O(l) → H₃O⁺(aq) + SO₄^2-(aq)
K_a2 = 1.2 × 10^–2

The larger value of
K_a1 (K_a1 >10) means that H2SO4 is largely
dissociated into H⁺ and HSO₄^–. Greater the value of dissociation constant(Ka), the stronger is the acid.

iv)Noble gases are inert because electronic configuration of noble gas is ns² np⁶ they contain a 'stable octet' of electrons in the outermost shell of the atom (valence electrons). This means that the noble gases do not need to react to lose or gain electrons in order to become stable, since scientists have determined that 8 valence electrons is a stable electron configuration.

v) Nitrogen is small in size and nitrogen has unique ability to form pπ -pπ multiple bonds with itself and with other elements having small size and high electronegativity (e.g., C, O).

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710. Describe the following about halogen family (group 17 elements):
(i)    Relative oxidising power.
(ii)    Relative acidic strength of their hydrides.
(iii)    Oxyacids and their relative oxidising ability.

656 Views