Title 4.13TH GROUP FINAL- PHANI SIR.pdf ✅

13TH GROUP 126 NISHITH Multimedia India (Pvt.) Ltd., JEE ADVANCED- VOL - III NISHITH Multimedia India (Pvt.) Ltd., 13TH GROUP(IIIA GROUP) SYNOPSIS BORON Boron exists in many allotropic forms. All the allotropes have basic building B12 icosahedral units made up of polyhedron having 20 faces and 12 corners.For example one is the simplest form :  - rhombohedral boron. Isolation of "B": (i) Preparation of B2O3 from Borax or Colemanite Na2B4O7 + HCl/H2 SO4  NaX + H2B4O7 H B O 5H O 4H BO B O H O 2 4 7 2 3 3 2 3 2      (ii) Reduction of B2O3 B2O3 + Na/K/Mg/Al  B + Na2O/K2O/MgO/Al 2O3 Chemical Props.: (i) Burning in air : 4 B + 3O2  2B2O3 4Al + 3O2  2Al2O3 (ii) Reaction with water B + H2O (Cold & hot)  no reaction 2B + 3H2O  B2O3 + H2 (red hot) Al + 3H2O  Al(OH)3 + 2 3 H2 (iii) B + HCl  no reaction B + H2 SO4 (dil) no reaction 2B + 3H2 SO4 (conc.)  2H3BO3 + 3SO2 B + 3HNO3  H3BO3 + 3NO2   2 4 2 4 2 2 3 2Al 6H SO Al SO 3SO 6H O     Al + HNO3 (80%)  Al2O3 (passive layer) and does not react further. (iv) 2B + 2NaOH + 2H2O  2NaBO2 + 3H2 2Al + 2NaOH + 2H2O  2NaAlO2 + 3H2 (v) 2B + N2  2BN 2Al + N2  2AlN 4B + C  B4C 4Al + 3C  Al4C3 (vi) 3Mg + 2B  Mg3B2 Preparation of B2H6 : (i) Mg3B2 + HCl  B2H6 + B4H10 + B5H9 etc. (10%) (ii) B4H10 100C  B2H6 + H2 + higher borane (iii) BCl3 or(BBr3 )+ 6H2 dischargeatlow pressure Electric B2H6 + 6HCl (iv) 3LiAlH4 + 4BF3  3LiF + 3AlF3 + 2B2H6 or LiBH4 or 3(BF3 ) Reaction of B2H6 : (i) B2H6 + O2 air spontaneously burnsin B2O3 + H2O (ii) B2H6 + H2O (Cold)  H3BO3 + 6H2 (iii) B2H6 + HCl (dry) AlCl3 anh.   B2H5Cl + H2 Orthoboric Acid H3BO3 is soluble in water and behaves as weak monobasic acid. It does not donate protons like most the acids, but rather it accepts OH– . It is therefore is Lewis acid (B(OH)3 ) B(OH)3 + 2H2O H3O+ + [B(OH)4 ] – or H3BO3 Since B(OH)3 only partially reacts with water to form H3O+ and [B(OH)4 ] – it behaves as a weak acid. Thus it cannot be titrated satisfactorily with NaOH as a sharp end point is not obtained. If certain polyhydroxy compounds such as glycerol, mannitol or sugar are added to the
NISHITH Multimedia India (Pvt.) Ltd., 127 JEE MAINS - CW - VOL - I JEE ADVANCED- VOL - III 13TH GROUP NISHITH Multimedia India (Pvt.) Ltd., titration mixture then B(OH)3 behaves as a strong monobasic acid. and hence can now be titrated with NaOH and end point is diluted using phenolphthalein as indicator. B(OH)3 + NaOH Na[B(OH)4 ] + NaBO2 + 2H2O The added compound must be a as diol to enhance the acidic proprieties in this way the cis- diol forms very stable complexes with [B(OH)4 ] – formed in forward direction above, thus effectively removing it from solution. Hence reaction proceeds in forward direction (Le- Chatelier principle.) C C C C C OH OH OH –2H O2 –2H O2 OH OH HO HO O O O O O O HO HO B B B C OH C C C C + + Heating of boric acid : H3BO3  100C HBO2 Metaboric acid  140C H2B4O7 red hot  B2O3 tetraboric acid H3BO3 + H2O2(H2O)+ (HO)2B–O–O–H  NaOH Na2 · 6H2O Sodium peroxy borate used in washing powder as brightener Preparation of Borax : Uses of borax: (i) In making glass, enamel and glaze of pottery. (ii) As antiseptic in medicinal soaps preparation. Chemical Properties of Aluminimum: (1) Reaction with Air at Water Al should react air to form a very thin oxide film (10–4 to 10–6 mm thick) on the surface and protects the metal from further attack 2 Al(s) + 2 3 O2 (g)  Al2O3 (s) H° = – 1670 kJ/mole (Thermal reaction) Ga and In are attacked neither by cold water nor hot water unless oxygen is present. T form an oxide on surface. (2) Reaction with Oxides and Bases Al dissolve in dilute mineral acids liberating H2 2Al + 6HCl  2AlCl3 + 3H2 Al also dissolves in aqueous NaOH ( amphoteric) liberating H2 and forming aluminates 2Al + 2NaOH + 6H2O  2 Na[Al(OH)4 ] + H2 or 2NaAlO2 + 2H2O Ga, In, T dissolve in dilute acids liberating H2 Ga is amphoteric like Al and it dissolves in aq. NaOH liberating H2 and forming gallates. Al2O3 preparation : (i) 2Al(OH)3 300 C Al2O3 + 3H2O (ii) Al2 (SO4 ) 3   Al2O3 + 3SO3
13TH GROUP 128 NISHITH Multimedia India (Pvt.) Ltd., JEE ADVANCED- VOL - III NISHITH Multimedia India (Pvt.) Ltd., (iii) (NH4 ) 2 SO4 · Al2 (SO4 ) 3 ·24H2O   Al2O3 + 2NH3 + 4SO3 + 25H2O Uses: (i) In making refractory brick (ii) as abrasive (iii) To make high alumina cement AlCl3 preparation: (i) 2Al + 6HCl (vap.)  2AlCl3 + 3H2 (over heated) dry (ii)   Al O 3C 3Cl 2AlCl vap. 3CO 2 3 2 3 1000 C       Props: (i) Its anhydrous formed is deliquescent and fumes in air. (ii) It sublimes at 180°C. (iii) It is covalent and exists in the form of dimer even if in non polar solvents e.g. alc., ether, benzene, where it is soluble in fair extent. Uses:(i) Friedel-Craft reaction (ii) Dyeing, drug. & perfumes etc. Alumns: M2 SO4 , ' M2 (SO4 ) 3 ·24 H2O Props: Swelling characteristics where M = Na+ , K+ , Rb+ , Cs+ , As+ , Tl+ ,  NH4 M' = Al+3, Cr+3, Fe+3, Mn+3, Co+3 K2 SO4 ·Al2 (SO4 ) 3 ·24H2O Potash alum (NH4 ) 2 SO4 ·Al2 (SO4 ) 3 ·24H2O Ammonium alum K2 SO4 ·Cr2 (SO4 ) 3 ·24H2O Chrome alum (NH4 ) 2 SO4 ·Fe2 (SO4 ) 3 ·24H2O Ferric alum Preparation: Al2O3 + 3H2 SO4  Al2 (SO4 ) 3 + 3H2O Al2 (SO4 ) 3 + K2 SO4 + aq. soln  crystallise Uses:(i) Act as coagulant (ii) Purification of water (iii) Tanning of leather (iv) Mordant in dying (v) Antiseptic LEVEL-V SINGLE ANSWER QUESTIONS 1. TlI3 is an ionic compound which furnishes any of the following ions A) Tl I & 3   B) 3 3 & Tl I   C) 3 & Tl I   D) & Tl I   2. The stability of +1 oxidation state increases in the sequence A) Tl In Ga Al    B) In Tl Ga Al    C) Ga In Al Tl    D) Al Ga In Tl    3. Which of the following is incorrect about borax? A) Produce alkaline solution in water B) Produce buffer solution in water C)Produce blue bead on heating with CaSO4 D) used as a flux 4. Which of the following salt act as strong oxidizing agent ? A) 3 Tl  B) 1 Tl  C) 3 Ga D) 3 In 5. Aluminium is more reactive than iron, But aluminium is less easily corroded than iron because: A) Aluminium is noble metal B) Oxygen forms a protective oxide layer C) Iron undergoes reaction easily with water D) Iron forms both mono and divalent ions 6. 2 4 7 2 Na B O H O 10 is correctly represented as A) 2 2 2 3 2 2 . .10 NaBO Na B O H O B) 2 4 5 2  4 Na B O OH H O  .8   C) 2 4 2 7 2  4 Na B H O O H O  .6   D) All are correct
NISHITH Multimedia India (Pvt.) Ltd., 129 JEE MAINS - CW - VOL - I JEE ADVANCED- VOL - III 13TH GROUP NISHITH Multimedia India (Pvt.) Ltd., 7. Boric acid on heating at 0 150 C gives A) B O2 3 B) H B O 2 4 7 C) HBO2 D) H BO 2 3 8. Which of the following combinations is not suitable for the preparation of Diborane A) NaBH I 4 2 & B)   Ca OH BCl 2 & 3 C) BCl H 3 2 & D) BF LiH 3  9. B H2 6 on reaction with tri methyl amine form a compound X. Hybridisation of B and N in that compound X is A) 3 2 SP SP & B) 2 2 SP SP & C) SP SP & D) 3 3 SP SP & 10. A mixture of ethyl alcohol and boric acid burns with green edged flame. The green edged flame contains A) Triethyl borate B) ethyl boride C) Acetaldehyde D) diborane 11. Orthoboric acid is A) a mono basic Arrhenius acid B) mono basic lewis acid C) tribasic Arrhenius acid D) Tribasic lewis acid 12. B H2 6 reacts with excess of NH3 at low temperature to form an addition product. The product is A) 2 6 3 B H NH .2 B) 2 6 3 B H NH .3 C) 2 6 3 B H NH .4 D)   2 3 6 B NH 13. Which of the following is not formed as product in the reaction ? Re 2 4 7 4 2 dhot Na B O NH Cl   A) BN B) B O2 3 C) NaCl D) B N H 3 3 6 14. Select the incorrect statement. A) NaOH can be stored in a vessel made of aluminium B) HNO3 can be stored in a vessel made of Be/ Aluminium alloy C) HF can be stored in a vessel coated of wax D) HF attacks glass 15. Diborane forms adduct with A) PF3 B) BF3 C) H  D) NH4  16. A coloured salt of cobalt is subjected to borax bead test. The transparent borax bead turns blue. From the given reaction, identify the one which does not take place during the process A) 2 2 2 7 2 3 4NaBO CO Na BO Na CO    B) 2 4 7 2 2 3 Na B O NaBO B O   2 C)   2 4 5 2 2 4 7 2 4 Na B O OH H O Na B O H O  .8 10     D) 2 3 2   2 CoO B O Co BO   (blue) 17.   3 2 6 . excess NH at hightemp whitecrystaline solid nB H A  A is Isostructural with A) Benzene B) Borazole C) Boron Nitrate D) Graphite 18. Borax is used as a cleaning agent because on dissolving in water it gives A) Alkaline solution B) Acidic solution C) Bleaching solution D) Neutral solution 19. Boric acid is a very weak acid but in presence of certain organic compounds, it acts as a strong acid. Which one of the following organic compounds can affect such change? A) Glycerol B) Acetic acid C) Ethyl alcohol D) Ethylene 20. B2O3 can be converted to BCl3 by heating A) B2O3 with Cl2 gas in the presence of SiO2 B) B2O3 with HCl gas C) B2O3 with NaCl in solid state D) A mixture of B2O3 and Carbon in dry Cl2 gas 21. Which of the following is only acidic in nature? A)  2 Be OH B)   Mg OH 2 C)  3 B OH D)  3 Al OH 22. Covalent character is maximum for A) AlF3 B) AlCl3 C) AlBr3 D) Al I3