Scattering of light

Ca(OH)₂ ⇌ Ca²⁺ + 2OH^-
Given that pH = 9
pOH = 14 - 9 = 5
[pOH = - log₁₀ [OH]]
[OH^-] = 10 ^[pOH]
[OH] = 10^-5 M
Ksp = [Ca²⁺] [OH^-]
= 10^-5/2 x (10^-5)²  = 0.5 x 10^-15

a) Fe²⁺  b) Fe³⁺  c) Fe⁰

Mn²⁺ ⇒ 3d⁵ contains 5 unpaired electrons
n = 5,
\( \sqrt{n(n+ 2)} \) BM
\(= \sqrt{5(5+ 2)} = \sqrt{35} = 5.92 BM\)

(i) For a strong electrolyte, at high concentration, the number of constituent ions of the electrolyte in a given volume is high and hence the attractive force between the oppositely charged ions is also high.
(ii) Moreover the ions also experience a viscous drag due to greater solvation.
(iii) These factors attribute for the low molar conductivity at high concentration.

(ii) 2,4-dichlorobenzaldehyde.

(iii) ethanal

K_sp = 1.8 \(\times\)10^-10, [AgNO₃]= 1 M
\(\mathrm{AgCl}_{(\mathrm{s})} \rightleftharpoons \mathrm{Ag}_{(\mathrm{aq})}^{+}+\mathrm{Cl}_{(\mathrm{aq})}^{-} \)
                    s            s
\(\mathrm{AgNO}_{3(\mathrm{aq})} \rightleftharpoons \mathrm{Ag}_{(\text {aq })}^{+}+\mathrm{NO}_{3_{(\text {aq })}}^{-}\\ 1 \mathrm{M} \quad \quad \quad \quad \quad 1 \mathrm{M} \quad \quad 1 \mathrm{M} \)
\(\left[\mathrm{Ag}^{+}\right]=(\mathrm{s}+1) \approx 1 \quad(\therefore \mathrm{s}<<1) \)
\(\left[\mathrm{Cl}^{-}\right]=\mathrm{s} \)
\(\mathrm{K}_{\mathrm{sp}}=\left[\mathrm{Ag}^{+}\right]\left[\mathrm{Cl}^{-}\right] \)
\(1.8 \times 10^{-10}=(1)(s) \)
\(\therefore \mathrm{s}=1.8 \times 10^{-10} \mathrm{M}\)

Conjugate Pairs:
\((a) \mathrm{HS}_{\text {(aq) }}^{-} \& \mathrm{H}_{2} \mathrm{~S}_{\text {(aq) }} \) \((b) \mathrm{HF}_{\text {(aq) }} \& \mathrm{~F}_{\text {(aq) }}^{-} \)
\((a) \mathrm{HPO}_{4}^{2-} \& \mathrm{PO}_{4}^{3-} \) \((b) \mathrm{SO}_{3}^{2-} \& \mathrm{HSO}_{3}^{-} \)
\((a) \mathrm{NH}_{4}^{+} \& \mathrm{NH}_{3} \) \((b) \mathrm{CO}_{3}^{2-} \& \mathrm{HCO}_{3}^{-}\)

(i) I Order reaction
(ii) S^-1
(iii) \({ t }_{ \frac { 1 }{ 2 } }\) = 0.693/k

Element of group 15 have stable half-filled p-orbitals hence large amount of energy is required to remove electrons as compared to group 16, which has an incomplete p subshell.

(i) The complex ion of the coordination compound containing the central metal atom/ion and the ligands attached to it is collectively called coordination sphere and are usually enclosed in square brackets with the net charge.
(ii) The other ionisable ions, are written outside the bracket are called counter ions. For example, the coordination compound K₄[Fe(CN)₆] contains the complex ion [Fe(CN)₆]^4- and is referred as the coordination sphere.
(iii) The other associated ion K⁺ is called the counter ion.

(i) Distillation is employed for low boiling volatile metals like zinc (boiling point 1180 K) and mercury (630 K).
(ii) In this method, the impure metal is heated to evaporate and the vapours are condensed to get pure metal.

(i) Zeolites are three-dimensional crystalline solids containing Al, Si and O in their regular three dimensional framework.
(ii) They are hydrated sodium alumino silicates with general formula Na₂O(AI₂O₃).·x(SiO₂)·yH₂O
(x = 2 to 10; y = 2 to 6).
(iii) Zeolites have porous structure in which the monovalent sodium ions and water molecules are loosely held.
(iv) The Si and Al atoms are tetrahedrally coordinated with each other through shared oxygen atoms.
(v) Zeolites are similar to clay minerals but they differ in their crystalline structure.
(vi) Zeolites have a three dimensional crystalline structure looks like a honeycomb consisting of a network of interconnected tunnels and cages.
(vii) Water molecules moves freely in and out of these pores but the zeolite framework remains rigid
(viii) Another special aspect of this structure is that the pore/channel sizes are nearly uniform, allowing the crystal to act as a molecular sieve.

(i) Aryl cyanide cannot be prepared in this method because of their less reactivity towards nucleophilic substitution. Aryl cyanides are prepared using Sandmeyers reactions.
\(KCH+\underset { methyl \ bromide }{ { CH }_{ 3 }-Br } \rightarrow \underset { ethanenitrile }{ { CH }_{ 3 }-CN } +KBr\)
(ii) By dehydration' of primary amides a aldoximes with P₂O₅
\(\underset { Acetamide }{ { CH }_{ 3 }-CO{ NH }_{ 2 } } \xrightarrow [ { -H }_{ 2 }O ]{ { P }_{ 2 }{ O }_{ 5 } } \underset { Ethaneitrile }{ { CH }_{ 3 }-{ CN } } \)
(iii) \(\underset { Acetaldoximes }{ { CH }_{ 3 }-CH=NOH } \xrightarrow [ { -H }_{ 2 }O ]{ { P }_{ 2 }{ O }_{ 5 } } \underset { Ethaneitrile }{ { CH }_{ 3 }-{ CN } } \)

The free radical polymeristion of the monomer, 2-c Woro buta -1,3-diene( chloroprene) gives neoprene.

It is superior to rubber and resistant to chemical action.
Uses: It is used in the manufacture of chemical containers, conveyer belts

On oxidation with nitric acid, it gives glycolic acid and tartaric acids which contain smaller number of carbon atoms than in fructose.

This shows that a keto group is present in C-2.

Oxidation half cell : A metallic zinc strip that dips into an aqueous solution of zinc sulphate taken in a beaker.
Reduction half cell : A copper strip that dips into an aqueous solution of copper sulphate taken in a beaker.

(i) Glycerol is prepared in a large scale by the hydrolysis of oils or fats either by using alkali or by super heated steam.
(ii) During this process, soap is formed along with the byproduct glycerol and this process is called saponification.

Uses of glycerol:
(i) Glycerol is used as a sweetening agent in confectionery and beverages.
(ii) It is used in the manufacture of cosmetics and transparent soaps.
(iii) It is used in making printing inks and stamp pad ink and lubricant for watches and clocks.
(iv) It is used in the manufacture of explosive like dynamite and cordite by mixing it with chaina clay.

\(\underset {Phenol} {\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}}+\mathrm{Zn}(\text { dust }) \rightarrow \underset {benzene(A)} {\mathrm{C}_{6} \mathrm{H}_{6}}+\mathrm{ZnO}\)

(i) In lyophillic colloids or sols definite attractive force or affinity exists between dispersion medium and dispersed phase. Examples: sols of protein and starch. They are more stable and will not get precipitated easily. 
(ii) In a lyophobic colloids, no attractive force exists between the dispersed phase and dispersion medium. They are less stable and precipitated readily, but cannot be produced again by just adding the dispersion medium. 
Examples: sols of gold, silver, platinum and copper.

(i) When potassium dichromate is heated with any chloride salt in the presence of Conc. H₂SO₄, orange red vapours of chromyl chloride (CrO₂CI₂) is evolved.
(ii) This reaction is used to confirm the presence of chloride ion in inorganic qualitative analysis

(iii) The chromyl chloride vapours are dissolved in sodium hydroxide solution and then acidified with acetic acid and treated with lead acetate. A yellow precipitate of lead chromate is obtained

(i) The crushed ore of gold is leached with aerated dilute solution of sodium cyanide.
(ii) Gold is converted into a soluble cyanide complex.
(iii) The gangue, aluminosilicate remains insoluble
\({ 4Au }_{ (s) }+{ 8CN }_{ (aq) }^{ - }+{ O }_{ 2(g) }+2{ H }_{ 2 }{ O }_{ (l) }\longrightarrow 4\left[ Au(CN)_{ 2 } \right] +_{ (aq) }^{ - }+{ 4OH }_{ (aq) }^{ - }\)

(i) Ionic solids have high melting points.
(ii) These solids do not conduct electricity, because the ions are fixed in their lattice positions.
(iii) They are hard so strong external force can change the relative positions of ions.

(i) From the molecular formula, (A) is identified as benzaldehyde and it is called as oil of bitter almonds.
(ii) Benzaldehyde is oxidised to benzoic acid by alkaline permanganate which gives brisk effervescence with NaHCO₃.
 \(\underset { (A) }{ { C }_{ 6 }{ H }_{ 5 }CHO } \overset { (O) }{ \longrightarrow } \underset { (B) }{ { C }_{ 6 }{ H }_{ 5 } } -COOH\)
(iii) When benzaldehyde is refluxed with aqueous alcoholic KCN, benzoin (C) is formed.
\({ C }_{ 6 }{ H }_{ 5 }CH=O+H-\overset { \underset { || }{ O } }{ C } -{ C }_{ 6 }{ H }_{ 5 }\overset { alc }{\underset{KCN} \longrightarrow } { C }_{ 6 }{ H }_{ 5 }-\underset { \overset { | }{ OH\\ (C) } }{ CH } -\overset { \underset { || }{ O } }{ C } -{ C }_{ 6 }{ H }_{ 5 }\)

(i) For a chemical reaction, catalyst is needed in very small quantity.
(ii) There may be some physical changes, but the catalyst remains unchanged in mass and chemical composition in a chemical reaction.
(iii) A catalyst itself cannot initiate a reaction. 
(iv) A solid catalyst will be more effective if it is taken in a finely divided form.
(v) A catalyst are specific in nature.
(vi) In an equilibrium reaction, presence of catalyst reduces the time for attainment of equilibrium and hence it does not affect the position of equilibrium and the value of equilibrium constant.
(vii) A catalyst is highly effective at a particular temperature called as optimum temperature.
(viii) Presence of a catalyst generally does not change the nature of products

(i) It oxidises ferrous salts to ferric salts.
 Cr₂O₇^2- + 6Fe²⁺+ 14H⁺ ⟶ 2Cr³⁺ + 6Fe³⁺ + 7H₂O
(ii) It oxidises iodide ions to iodine
Cr₂O₇^2- + 6I^-+ 14H⁺ ⟶ 2Cr³⁺ + 3I₂ + 7H₂O
(iii) It oxidises sulphide ion to sulphur
Cr₂O₇^2- + 3S^2-+ 14H⁺ ⟶ 2Cr³⁺ + 3S + 7H₂O
(iv) It oxidises sulphur dioxide to sulphate ion
Cr₂O₇^2- + 3SO₂+ 2H⁺ ⟶ 2Cr³⁺ + 3SO₄^2- + H₂O
(v) It oxidises stannous salts to stannic salt
 Cr₂O₇^2- + 3Sn²⁺ + 14H⁺ ⟶ 2Cr³⁺ + 3Sn⁴⁺ + 7H₂O
(vi) It oxidises alcohols to acids
2K₂Cr₂O₇ + 8H₂SO₄ + 3CH₃CH₂OH ⟶ 2K₂SO₄ +2Cr₂(SO₄)₃+ 3CH₃COOH + 11H₂O
(vii) It oxidises oxalic acid to CO2
2MnO₄^- + 5(COO)^2- + 6H⁺ ⟶ 2Mn²⁺+ 10CO₂ + 8H₂O
(viii) It oxidises iodide ions to iodine
2MnO4^- + 10I^- + 16H⁺ ⟶ 2Mn²⁺+ 5I₂+ 8H₂O
(ix) It oxidises sulphide ion to sulphur
2MnO₄^- + 5S^2-+ 16H⁺ ⟶ 2Mn²⁺+ 5S + 8H₂O
(x) It oxidises nitrites to nitrates
 2MnO₄^- + 5NO^2- + 6H⁺ ⟶ 2Mn²⁺+ 5NO₃^- + 3H₂O
(xi) It oxidises alcohols to aldehydes.
 2KMnO₄ + 3H₂SO₄ + 5CH₃CH₂OH ⟶ 2K₂SO₄ + 2MnSO₄ + 5CH₃CHO + 8H₂O
(xii) It oxidises sulphite to sulphate
2MnO₄^- + 5SO₃^2- + 6H⁺ ⟶ 2Mn²⁺ + 5SO₄^2- + 3H₂O

Manufacture of sulphuric acid by contact process:
The contact process involves the following steps.
(i) Initially sulphur dioxide is produced by burning sulphur or iron pyrites in oxygen/ air.
\(S+{ O }_{ 2 }\longrightarrow { SO }_{ 2 }\)
\({ 4FeS }_{ 2 }+{ 11O }_{ 2 }\longrightarrow { 2Fe }_{ 2 }{ { O }_{ 3 } }+8{ SO }_{ 2 }\)
(ii) Sulphur dioxide formed is oxidised to sulphur trioxide by air in the presence of a catalyst such as V₂O₅ or platinised asbestos.
(iii) The sulphur trioxide is absorbed in concentrated sulphuric acid and produces oleum (H₂S₂O₇). The oleum is converted into sulphuric acid by diluting it with water. 
\(\mathrm{SO}_{3}+\mathrm{H}_{2} \mathrm{SO}_{4} \longrightarrow \mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{7} \stackrel{\mathrm{H}_{2} \mathrm{O}}{\longrightarrow} 2 \mathrm{H}_{2} \mathrm{SO}_{4}\)
(iv) To maximise the yield the plant is operated at 2 bar pressure and 720 K. The sulphuric acid obtained in this process is over 96 % pure.

Schottky defect:
(i) Schottky defect arises due to the missing of equal number of cations and anions from the crystal lattice.
(ii) This effect does not change the stoichiometry of the crystal.
(iii) Ionic solids in which the cation and anion are of almost of similar size show schottky defect. Ex: NaCl.
(iv) Presence of large number of schottky defects in a crystal, lowers its density.

Frenkel defect:
(i) Frenkel defect arises due to the dislocation of ions from its crystal lattice.
(ii) The ion which is missing from the lattice point occupies an interstitial position.
(iii) This defect is shown by ionic solids in which cation and anion differ in size.
(iv) Unlike Schottky defect, this defect does not affect the density of the crystal.
(v) For example AgBr, in this case, small Ag⁺ ion leaves its normal site and occupies an interstitial position.

The coordination compounds can be classified into the following types based on (i) the net charge of the complex ion, (ii) kinds of ligands present in the coordination entity.
Classification based on the net charge on the complex: 
A coordination compound in which the complex ion.
(i) carries a net positive charge is called a cationic complex. Examples: [Ag(NH₃)₂]⁺, [Co(NH₃)₆]³⁺, [Fe(H₂O)₆]²⁺, etc.
(ii) carries a net negative charge is called an anionic complex. Examples: [Ag(CN)₂]^-, [Co(CN)₆]^3-, [Fe(CN)₆]^4-, etc.
(iii) bears no net charge, is called a neutral complex. Examples: [Ni(CO)₄],[Fe(CO)₅] [Co(NH₃)₃(CI)₃].
Classification based on kind of ligands:
A coordination compound in which
(i) the central metal ion/atom is coordinated to only one kind of ligands is called a homoleptic complex. Examples: [Co(NH₃)₆]^{3+ +,} [Fe(H₂O)₆]²⁺,
(ii) the central metal ion/atom is coordinated to more than one kind of ligands is called a heteroleptic complex. Example,  [Co(NH₃)₅CI]²⁺, [Pt(NH₃)₂CI₂)] 

(i) Order of the reaction =1; \(\mathrm{t}_{1 / 2}=60 \mathrm{~s} ; \mathrm{k}=?\)
\(\mathrm{k}=\frac{0.6932}{\mathrm{t}_{\frac{1}{2}}} \)
\(=\frac{0.6932}{60}  \)
\(k =1.155 \times 10^{-2} \mathrm{~s}^{-1}\)
(ii) \(\left[\mathrm{A}_{0}\right]=100 \% ; \mathrm{t}=180 \mathrm{~s} ;[\mathrm{A}]=? ; \mathrm{k}=1.155 \times 10^{-2} \mathrm{~s}^{-1}\)
For first order reaction
\(\mathrm{k}=\frac{2.303}{\mathrm{t}} \log \frac{\left[\mathrm{A}_{0}\right]}{[\mathrm{A}]} \)
\(1.155 \times 10^{-2} =\frac{2.303}{180} \log \left(\frac{100}{[A]}\right)  \)
\(\frac{0.01155 \times 180}{2.303} =\log \left(\frac{100}{[A]}\right)  \)
\(0.9027 =\log 100-\log [\mathrm{A}]  \)
\(\log [\mathrm{A}] =\log 100-0.9027 \)
\(\log [A]=2-0.9027 \)
\(\log [A]=1.0972 \)
[A] = antilog  of (1.0972)
[A] =12.51 %