Ncert Solutions Chemistry Class 12th

4.10  (i) 3NO (g)? N₂O (g)

Rate = k [NO]²

Here rate law is dependent on concentration of NO only. And power raised to concentration of NO is 2. Hence order of reaction is 2.

To find the dimensions of rate constant (K)- We know the rate of chemical reaction is measured in (concentration / time). So, the unit of K will be

(concentration) / (time) (concentration)²

 i.e. [concentration]^-1 [ time]^-1 . If concentration is in mol L^-1 and time is in sec. then dimensions of k will be : mol^-1 L sec^-1

(ii) H₂O₂ (aq) + 3I^- (aq) + 2H⁺? 2 H₂O (l) + I₃^-

Rate = k [H₂O₂] [I^-]

Here rate law is dependent on concentration of H₂O₂ and I^-. And power raised to concentration of H₂O₂ is 1, and power raised to concentration of I^- is 1. order is sum of powers hence, order of given reaction is 2.

To find dimensions of rate constant (K)- We know rate of chemical reaction is measured in [concentration/time]. So, unit of K will be [Concentration]/ [time] [concentration]² i.e. [concentration]^-1 [ time]^-1. If concentration is in mol L^-1 and time is in sec then dimensions of k will be mol^-1 L sec^-1

(iii) CH₃CHO (g)? CH₄ (g) + CO (g)

Rate = k [CH₃CHO]^3/2

Here rate law is dependent on concentration of CH₃CHO.And power raised to CH₃CHO is 3/2. Hence order of reaction is 3/2.

To find dimensions of rate constant (K)- We know rate of chemical reaction is measured in [concentration/time]. So, unit of K will be [Concentration]/ [time] [concentration]^3/2 i.e. [concentration]^-

^1/2 [time]^-1.

If concentration is in mol L^-1 and time is in sec. Then dimensions of K will be mol^-1/2L^1/2 sec^-1

(iv) C₂H₅Cl (g)? C₂H₄ (g) + HCl (g)

Rate = k [C₂H₅Cl]

Here rate law is dependent on concentration of C₂H₅Cl. And power raised to C₂H₅Cl is 1. Hence order of reaction is 1.

To find dimensions of rate constant (K)- We know the rate of chemical reaction is measured in [concentration/time]. So, unit of K will be [Concentration]/ [time] [concentration]¹. i.e. [time]^-1

If concentration is in mol L^-1 and time is in sec. Then the dimensions of K will be sec^-1.

Optical isomers are the one which rotate the plane polarized light by a certain angle when passed through them and are mirror images of each other, also called as stereoisomer.

(i) C₂O₄ ^2- is a bidentate ligand so it can attach to central atom at two sites, forming a chelate ring. In the complexes of this type, three symmetrical bidentate chelating ligands AA are coordinated to the central metal atom M. Such complexes do not possess any element of symmetry and are optically active. Moreover, these complexes can be resolved into optical

(ii) In this complex Cl is an unidentate ligand with one site of attachment whereas -en (ethylenediamine) is bidentate ligand with two sites of attachment. The complexes in which two symmetrical bidentate chelating ligands AA and two monodentate ligands a, are coordinated to central metal atom M, exhibit the phenomenon of optical isomerism and can be resolved into their optical

An example of this type of complexes is given as shows both geometrical as well as optical isomerism. Its cis form is unsymmetrical, while the trans form is symmetrical because it contains a plane of symmetry. Hence, optical isomerism is shown by cis form.

(iii) In this there are three types of ligands. One is ammonia which is neutral (nitrogen donates the lone pair of electron to metal), Cl ^- ligand is unidentate and -en is bidentate ligand. Coordination number is 6. Two optical isomers are possible due to presence of 3 types of

4.9 Given-

Energy of activation, E_a= 209.5 kJ mol^–1

E_a in joules = 209.5 * 1000 = 209500 J mol^–1

Temperature, T = 581K

Gas constant, R = 8.314 J K^-1 mol^-1

Using the Arrhenius equation,

k = Ae^-Ea/RT

In this equation, the term e^-Ea/RT represents the number of molecules which have kinetic energy greater than the activation energy, E_a.

∴The number of molecules = e^-Ea/RT → Equation 1. Substituting all the known values in equation 1, we get,

= e^{-209500/8.314X581}

=e^-43.3708

Finding the value of anti ln (43.3708), we get, 1.47 * 10^-19

The fraction of molecules of reactants having energy equal to or greater than activation energy is 1.47 * 10^-19

Isomers are the compounds which have same chemical formula but different arrangement of atoms in space. There are principle two types of isomerism:

(i) Stereo isomerism

(ii) Geometrical isomerism

(iii) Optical isomerism

(iv) Structural isomerism

(v) Ionisation isomerism

(vi) Linkage isomerism

(vii) Coordination isomerism

(viii) Solvate isomerism

Geometrical isomerism comes into existence by the different spatial arrangement of groups around the central metal atom. Similar groups may either be arranged on the same side or on opposite sides of the central metal atom. This gives rise to two types of isomers called cis and trans isomers. When groups under consideration are arranged on the same side of the central metal atom, isomers are called cis isomers and when the groups under consideration are spatially placed on the opposite sides, isomers are called trans isomer.

(i) Starting with cation, the complex ion contains six ammonia molecules with cobalt in + 3 oxidation The name of compound: [Co (NH₃)₆]Cl₃ is hexaamminecobalt (III) chloride.

(ii) The complex ion is cation, so there are 2 ammonia molecules, one chloride ion and methyammine molecule qith platinum in + 2 state. Going in alphabetical order, the name of compound: [Pt (NH₃)₂Cl (NH₂CH₃)]Cl is diamminechloridomethylammineplatinum (II)

(iii) It is a complex cation with six water molecules and titanium atom in + 3 state. The name of the compound: [Ti (H₂O)₆]³⁺ is hexaaquatitanium (III) ion

(iv) The complex ion is cation with cobalt in + 3 state and with four ammonia molecules etetraammine, one chloride ion and nitrate ion. The name of the compound: [Co (NH₃)₄Cl (NO₂)]Cl is tetraamminechloridonitritocobalt (III) chloride.

(v) The complex ion is cation with manganese in + 2 state and six water The name of compound: [Mn (H₂O)₆]²⁺ is hexaaquamanganese (II) ion.

(vi) The complex is anion with nickel in + 2 state and with four chloride ions. The name of the compound: [NiCl₄]^2– is tetrachloridonickeltate (II)

(vii) The complex is cation with nickel in + 2 state and six ammonia molecules. The name of compound: [Ni (NH₃)₆]Cl₂ is hexaamminenickel (II) chloride.

(viii) The complex is cationwithcobalt in + 3 stateand there is a bidentate ligand called as The name of compound : [Co (en)₃]³⁺ is tris (ethylenediamine)cobalt (III) ion.

(ix) It is neutral complex with four carbonyl molecules and cobalt in 0 state. The name of compound: [Ni (CO)₄] is tetracarbonylcobalt (0).