Class XI - Thermodynamics notes - Chapter 6

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Class XII: Assignment of p-Block and d & f-Block elements

P-block

Complete the following reactions :

1. (i) (NH4)2 Cr2O7¾¾heat®

    (ii) N4H Cl (aq) + NaNO2 (aq) ¾¾®

2. (i) NH2CONH2 + H2O ¾¾®

   (ii) FeCl3 (aq) + NH4OH ¾¾®

3. (i) Ca3 P2 + H2 O (l) ¾¾®

   (ii) I2 + HNO3 (conc.) ¾¾®

4. (i) Ba(N3)2¾¾heat®

   (ii) 4H3PO3¾¾heat®

5. (i) PH4I + KOH ¾¾®

   (ii) HgCl2 + PH3 ¾¾®

6. (i) PCl3 + 3H2O ¾¾®

   (ii) S + H2SO4 (conc.) ¾¾®

7. (i) Al2O3(s) + NaOH (aq) + H2O(l) ¾¾®

   (ii) HCl + O2 + CuCl¾¾¾¾®

8. (i) Ca(OH)2 + Cl2 ¾¾®

   (ii) XeF4 + H2O ¾¾®

9. (i) Na2SO3 + Cl2 + H2O ¾¾®

   (ii) NaHCO3 + HCl¾¾®

10. (i) XeF6 + H2O Completehydrolysis¾¾¾¾®

(ii) XeF6 + H2OPartialhydrolysis ¾¾¾¾®

11. (i) NO3– + Fe2+ + H+ ¾¾®

    (ii) Zn + HNO3 (dil) ¾¾®

12. (i) Zn + HNO3 (conc) ¾¾®

      (ii) P4 + HNO3 (conc) ¾¾®

13. (i) NH3 + O2¾¾Pt/Rh®

     (ii) P4 + NaOH + H2O ¾¾®

14. (i) P4 + SOCl2 ¾¾®

      (ii) P4 + SO2Cl2 ¾¾®

15. (i) PbS + O3 ¾¾®

     (ii) KI + H2O + O3 ¾¾®

16. (i) MnO4– + SO2 + H2O ¾¾®

(ii) Zn + HNO3(dil)¾¾®

17. (i) NH3 (Excess) + Cl2 ¾¾®

      (ii) NH3 + Cl2 (Excess) ¾¾®

18. (i) Cl2 + NaOH (cold and dil) ¾¾®

      (ii) Cl2 + NaOH (hot &conc) ¾¾®

19. (i) Fe + HCl¾¾®

      (ii) Cl2 + F2 (Excess) ¾¾®

20. (i) U + ClF3 ¾¾®

      (ii) FeSO4 + H2SO4 + Cl2 ¾¾®

21. (i) How is HNO3 prepared commercially?

(ii) Write chemical equations of the reactions involved.

(iii) What concentration by mass of HNO3 is obtained?

22. (i) How does O3 react with lead sulphide? Write chemical equation.

(ii) What happens when SO2 is passed in acidified KMnO4 solution?

23. An unknown salt X reacts with hot conc. H2SO4 to produce a brown coloured gas which intensifies on addition on copper turnings. On adding dilute ferrous sulphate solution to an aqueous solution of X and then carefully adding conc. H2SO4 along the sides of the test tube, a brown complex Y is formed at the interface between the solution and H2SO4. Identify X and

Y and write the chemical equation involved in the reaction.

24.A transluscent while waxy solid (A) on heating in an inert atmosphere is converted to its allotropic form (B), Allotrope (A) on reaction with very dilute aqueous NaOH liberates a highly poisonous gas (C) having a rotten fish smell, with excess of chlorine forms D which hydrolyses to form compound (E). Identify the compounds (A) to (E).

25. Write balanced equation for the following reactions :

(a) Zn is treated with dilute HNO3.

(b) NaCl is heated with H2SO4 in the presence of MnO2.

(c) Iodine is treated with conc. HNO3.

25. X2 is a greenish yellow gas with pungent offensive smell used in purification of water. It partially dissolves in H2O to give a solution which turns bluelitmus red. When X2 is passed through NaBr Solution, Br2 is obtained.

(a) Identify X2, name the group to which it belongs.

(b) What are the products obtained when X2 reacts with H2O? Writechemical equation.

(c) What happens when X2 reacts with hot and conc. NaOH? Giveequation.

26.How is PH3 prepared in the laboratory? How is it purified? How does the solution of PH3 in water react on irradiation with light and on absorption in CuSO4? How can you prove that PH3 is basic in nature?Write the chemical equations for all the reactions involved.

27. A white waxy, translucent solid, M, insoluble in water but soluble in CS2,glows in dark. M dissolves in NaOH in an inert atmosphere giving a poisonous gas (N). Also M catches fire to give dense white fumes of Q :

(a) Identify M, N and Q and write the chemical equations of the reactions involved.

(b) M exists in the form of discrete tetrahedral molecules. Draw its structure.

(c) M on heating at 573 K is changed into other less reactive form, Q, which is non-poisonous, insoluble in water as well as in CS2 and does not glow in dark, Identify Q and draw its structure.

                                       

D & F- block

1.The stability of Cu2+ (aq) is more than that of Cu+ (aq). Why?

2. Indicate the steps in the preparation of

(a) K2Cr2O7 from Chromite ore.

(b) KMnO4 from Pyrolusite ore.

3.(a) Why do transition metals show high melting points?

(b) Out of Fe and Cu, which one would exhibit higher melting point?

4. Describe giving reason which one of the following pairs has the property

indicated :

(a) Cr2+ or Fe2+ (stronger reducing agent).

(b) Co2+ or Ni2+ (lower magnetic moments).

5. Of the ions Co2+, Sc3+, Cr3+ which one will give colourless aqueous solution and how will each of them respond to magnetic field and why?

6. For the first row transition metals the enthalpy of atomisation value are :

ScTi     V    Cr  Mn   Fe  Co   Ni   Cu   Zn

∆aH/kJ mol–1 326 473 515 397 281 416 425 430 339 126

Assign reason for the following :

(a) Transition elements have higher values of enthalpies of atomisation.

(b) The enthalpy of atomisation of zinc is the lowest in 3d - series.

7. Account for the following :

(a) Copper shows its inability to liberate hydrogen gas from the dilute acids.

(b) Scandium (Z = 21) does not exhibit variable oxidation states.

8. Copper (I) compounds undergo disproportionation. Write the chemical equation for the reaction involved and give reason.

9.Account for the following :

(a) La(OH)3 is more basic than Lu(OH)3

(b) Zn2+ salts are white.

(c) Cu(I) compounds are unstable in aqueous solution and undergodisproportination.

10. Describe the oxidising action of potassium dichromate with following. Writeionic equations for its reaction with.(a) Iodide ion (b) Iron (II) (c) H2S.

11. (a) Deduce the number of 3d electrons in the following ions :

Fe3+, Cu2+ and Sc3+.

(b) Why do transition metals form alloys.

(c) Write any two characteristics of interstitial compounds.

12.(a) For M2+/M and M3+/M2+ systems, the Evalues for some metals are as follows :

Cr2+/Cr = – 0.9V and Cr3+/Cr2+ = – 0.4V

Mn2+/Mn = – 1.2 V and Mn3+/Mn2+ = + 1.5V

Fe2+/Fe = – 0.4V and Fe3+/Fe2+ = + 0.8V

Use this data to comment upon :

(i) the stability of Fe3+ in acid solution as compared to that of Cr3+ and Mn3+

(ii) the ease with which iron can be oxidised as compared to a similar process for either chromium or manganese.

(b) How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.

13.When a white crystalline compound A is heated with K2Cr2O7 and conc.H2SO4, a reddish brown gas B is evolved, which gives a yellow coloured solution C when passed through NaOH. On adding CH3COOH and(CH3COO)2 Pb to solution C, a yellow coloured ppt. D is obtained. Also on heating A with NaOH and passing the evolved gas through K2HgI4 solution, a reddish brown precipitate E is formed.Identify A, B, C, D and E and write the chemical equations for the reactions involved.

14.A green compound ‘A’ on fusion with NaOH in presence of air forms yellow compound ‘B’ which on acidification with dilute acid, gives orange solution of compound ‘C’. The orange solution when reacted with equimolarammonuim salt gives compound ‘D’ which when heated liberates nitrogen gas and compound ‘A’. Identify compounds A to D and write the chemical

equation of the reactions involved.

[Hint :‘A’ = CrO3; ‘B’ = Na2CrO4; ‘C’ = Na2Cr2O7 ‘D’ = (NH4)2 Cr2O7

15. Assign reasons for the following :

(a) There is no regular trends in E° values of M2+/M systems in 3d series.

(b) There is gradual decrease in the ionic radii of M2+ ion in 3d series.

(c) Majority of transition metals form complexes.

(d) Ce3+ can be easily oxidised to Ce4+

(e) Tantalum and palladium metals are used to electroplate coinage metals.

16. Account for the following :

(a) Actinoids display a variety of oxidation states.

(b) Yb2+ behaves as a good reductant.

(c) Cerium (iv) is a good analytical reagent.

(d) Transition metal fluorides are ionic in nature while chlorides and bromides are covalent in nature.

(e) Hydrochloric acid attacks all the actinoids.

17. Explain by giving suitable reason :

(a) Co(II) is stable in aqueous solution but in the presence of complexing agent it is readily oxidised.

(b) Eu2+, Yb2+ are good reductants whereas Tb4+ is an oxidant.

(c) AgCl dissolves in ammonia solution

(d) Out of Cr²⁺ or Fe²⁺, which one is a stronger reducing agent?

(e) The highest oxidation state is exhibited in oxoanions of a transition metal.

Class XII: Ouestions of Chapter - 10 & 11 (Organic Chemistry)

IMPORTANT QUESTION OF CH-10 & 11

1. An alcohol A (C4H10O) on oxidation with acidified potassium dichromategives carboxylic acid B (C4H8O2). Compound A when dehydrated withconc. H2SO4 at 443 K gives compound C. Treatment of C with aqueousH2SO4 gives compound D (C4H10O) which is an isomer of A. CompoundD is resistant to oxidation but compound A can be easily oxidised. Identify

A, B, C and D and write their structures.

2. An organic compound A having molecular formula C6H6O gives acharacteristic colour with aqueous FeCl3. When A is treated with NaOHand CO2 at 400 K under pressure, compound B is obtained. CompoundB on acidification gives compound C which reacts with acetyl chloride to

form D which is a popular pain killer. Deduce the structure of A, B, C andD. What is the common name of Drug D?

3. An ether A (C5H12O) when heated with excess of hot concentrated HIproduced two alkyl halides which on hydrolysis from compounds B and C.Oxidation of B gives an acid D whereas oxidation of C gave a ketone E.Deduce the structures of A, B, C, D and E.

4. Phenol, C6H5OH when it first reacts with concentrated sulphuric acid, formsY.Y is reacted with concentrated nitric acid to form Z. Identify Y and Z andexplain why phenol is not converted commercially to Z by reacting it withconc. HNO3.

5. Give reason for the following:

(i) The C–O–C bond angle in dimethyl ether is (111.7°)

(ii) Alcohols have higher boiling points than ethers of comparablemolecular masses.

(iii) Phenols are more acidic than alcohols.

(iv) Nitro phenol is more acidic than o-methoxyphenol.

(v) Phenol is more reactive towards electrophilic substitution reactionthan benzene.

(vi) The following is not an appropriate method for the preparation of1-methoxy-4-nitrobenzene;

(vii) Write the suitable reaction for the preparation of1–methoxy–4–nitrobenzene

(viii) o-nitrophenol is steam volatile but p-nitrophenol is not.

(ix) phenol is less polar than ethanol.

(x) The phenyl methyl ether reacts with HI fo form phenol and

iodomethane and not iodobenzene and methanol.

(xi) methanol is less acidic than water.

(xii) alcohols can act as weak base as well as weak acids.

(xiii) phenols do not give protonation reaction readily.

(xiv) absolute ethanol can not be obtained by factional distillation of ethanoland water mixture.

6. Arrange the following in the increasing order of property shown :

(i) methanol, ethanol, diethylether, ethyleneglycol. (Boiling points)

(ii) phenol, o-nitrophenol, m-nitrophenol, p-nitrophenol. (Acid strength)

(iii) dimethylether, ethanol, phenol. (Solubility in water)

(iv) n-butanol, 2-methylpropan-1-ol, 2-methylpropan-2-ol. (Acid strength)

7. Give a chemical test to distinguish between the following pair of compounds.

(i) n-propyl alcohol and isopropylalcohol

(ii) methanol and ethanol

(iii) cyclohexanol and phenol.

(iv) propan-2-ol and 2-methylpropan-2-ol.

(v) phenol and anisole

(vi) ethanol and diethyl ether

8. An organic compound (A) having molecular formula C3H7Cl on reactionwith alcoholic solution of KCN gives compound B. The compound B onhydrolysis with dilute HCl gives compound C. C on reduction withH2/ Ni gives 1-aminobutane. Identify A, B and C.

An optically active compound having molecular formula C7H15Br reactswith aqueous KOH to give C7H15OH, which is optically inactive. Givemechanism for the reaction.A racemic mixture is obtained which is optically inactive.

9. An organic compound C8H9Br has three isomers A, B and C. A is opticallyactive. Both A and B gave the white precipitate when warmed with alcoholicAgNO3 solution in alkaline medium. Benzoic acid, terephthalic and pbromobenzoicacid were obtained on oxidation of A, B and C respectively.Identify A, B and C.

10. An alkyl halide X having molecular formula C6H13Cl on treatment withpotassium tert-butoxide gives two isomeric alkenes Y and Z but alkene yis symetrical. Both alkenes on hydrogenation give 2, 3-dimethylbutane.

Identify X, Y and Z.

11.Give reasons for the following :

(i) The bond length of C–Cl bond is larger in haloalkanes than that inhaloarenes.

(ii) Although alkyl halides are polar in nature but are not soluble inwater.

(iii) tert-butyl bromide has lower boiling point than n-Butyl bromide.

(iv) haloalkanes react with KCN to form alkyl cyanide as main productwhile with AgCN alkyl isocyanide is the main product.

(v) sulphuric acid is not used in the reaction of alcohol with Kl.

(vi) thionyl chloride is the preferred reagent for converting ethanol tochloroethane.

(vii) haloalkanes undergo nucleophilic substitution reaction easily buthaloarenes do not undergo nucleophilic substitution under ordinaryconditions.

(viii) chlorobenzene on reaction with fuming sulphuric acid gives orthoand para chlorosulphonic acids.

(ix) 2, 4-dinitro chlorobenzene is much more reactive than chlorobenzenetowards hydrolysis reaction with NaOH.

(x) Grignard reagent should be prepared under anhydrous conditions.

(xi) the dipole moment of chlorobenzene is lower than that of cyclohexylchloride.

(xii) neopentyl bromide undergoes nucleophilic substitution reactions veryslowly

(xiii) vinyl chloride is unreactive in nucleophilic substitution reaction.

(xiv) An optically inactive product isobtained after the hydrolysis ofoptically active 2- bromobutane.

12.Arrange the following in the increasing order of properly indicated :

(i) bromomethane, chloromethane, dichloromethane. (Increasing order

of boiling points).

(ii) 1-chloropropane, isopropyl chloride, 1-chlorobutane (Increasing order

of boiling point)

(iii) dichloromethane, chloroform, carbon terachloride. (Increasing order

of dipole moment.

(iv) CH3F, CH3Cl, CH3Br, CH3l (Increasing reactivity towards nucleophilic

substitution and increasing order of dipole moment)

(v) o,m.p-dichlorobenzenes (Increasing order of melting points).

13.Arrange the following in the increasing order of properly indicated :

(i) bromomethane, chloromethane, dichloromethane. (Increasing orderof boiling points).

(ii) 1-chloropropane, isopropyl chloride, 1-chlorobutane (Increasing orderof boiling point)

(iii) dichloromethane, chloroform, carbon terachloride. (Increasing orderof dipole moment.

(iv) CH3F, CH3Cl, CH3Br, CH3l (Increasing reactivity towards nucleophilicsubstitution and increasing order of dipole moment)

(v) o,m.p-dichlorobenzenes (Increasing order of melting points).

14. How will you bring about the following conversions?

(i) benzene to 3-bromonitrobenzene

(ii) ethanol to but-1-yne

(iii) 1-bromopropane to 2-bromopropane

(iv) benzene to 4-bromo-1-nitrobenzene

(v) aniline to chlorobenzene

(vi) 2-methyl-1-propene to 2-chloro-2-methylpropane

(vii) ethyl chloride to propanoic acid

(viii) but-1-ene to n-butyl iodide

(ix) benzene to phenylchloromethane.

(x) tert-butyl bromide to isobutyl bromide.