Class 11 Chemistry - Chapter Redox Reactions NCERT Solutions | Justify giving reactions that among halo

Balance the following redox reactions by ion – electron method :

(a) MnO₄ ^– (aq) + I ^– (aq) → MnO_{2 (s)} + I_2(s) (in basic medium)

(b) MnO₄ ^– (aq) + SO_{2 (g)} → Mn²⁺ (aq) + HSO₄^– (aq) (in acidic solution)

(c) H₂O_{2 (aq)} + Fe ²⁺ (aq) → Fe³⁺ (aq) + H₂O (l) (in acidic solution)

(d) Cr₂O₇ ^2– + SO_2(g) → Cr³⁺ _(aq) + SO₄^2– (aq) (in acidic solution)

Assign oxidation number to the underlined elements in each of the following species:

(a) NaH₂PO₄

(b) NaHSO₄

(c) H₄P₂O₇

(d) K₂MnO₄

(e) CaO₂

(f) NaBH₄

(g) H₂S₂O₇

(h) KAl(SO₄)₂.12 H₂O

What are the oxidation number of the underlined elements in each of the following and how do you rationalise your results ?

(a) KI₃

(b) H₂S₄O₆

(c) Fe₃O₄

(d) CH₃CH₂OH

(e) CH₃COOH

Justify that the following reactions are redox reactions:

(a) CuO_(s) + H_2(g) → Cu_(s) + H₂O_(g)

(b) Fe₂O_3(s) + 3CO_(g) → 2Fe_(s) + 3CO_2(g)

(c) 4BCl_3(g) + 3LiAlH_4(s) → 2B₂H_6(g) + 3LiCl_(s) + 3 AlCl_{3 (s)}

(d) 2K_(s) + F_2(g) → 2K⁺F^– _(s)

(e) 4 NH_3(g) + 5 O_2(g) → 4NO_(g) + 6H₂O_(g)

Balance the following equations in basic medium by ion-electron method and oxidation number methods and identify the oxidising agent and the reducing agent.

(a) P_4(s) + OH ^– _(aq)  →  PH_3(g) + HPO^{2 –} _(aq)

(b) N₂H_4(l) + ClO^{3 –} _(aq)  →  NO_(g)  +  Cl^–_(g)

(c) Cl₂O_{7 (g)}  +  H₂O_2(aq)  →  ClO ^– _2(aq)   +  O_2(g)  +  H ⁺ _(aq)

Fluorine reacts with ice and results in the change:

H₂O_(s) + F_2(g) → HF_(g) + HOF_(g)

Justify that this reaction is a redox reaction.

Write the formulae for the following compounds:
(a) Mercury(II) chloride
(b) Nickel(II) sulphate
(c) Tin(IV) oxide
(d) Thallium(I) sulphate
(e) Iron(III) sulphate
(f) Chromium(III) oxide

While sulphur dioxide and hydrogen peroxide can act as oxidising as well as reducing agents in their reactions, ozone and nitric acid act only as oxidants. Why?

Identify the substance oxidised, reduced, oxidising agent and reducing agent for each of the following reactions:

(a) 2AgBr _(s) + C₆H₆O_2(aq) → 2Ag_(s) + 2HBr _(aq) + C₆H₄O_2(aq)

(b) HCHO_(l) + 2[Ag (NH₃)₂]⁺_(aq) + 3OH^-_(aq) → 2Ag_(s) + HCOO^-_(aq) + 4NH_3(aq) + 2H₂O_(l)

(c) HCHO _(l) + 2Cu²⁺_(aq) + 5 OH^-_(aq) → Cu₂O_(s) + HCOO^-_(aq) + 3H₂O_(l)

(d) N₂H_4(l) + 2H₂O_2(l) → N_2(g) + 4H₂O_(l)

(e) Pb_(s) + PbO_2(s) + 2H₂SO_4(aq) → 2PbSO_4(s) + 2H₂O_(l)

The compound AgF₂ is an unstable compound. However, if formed, the compound acts as a very strong oxidizing agent. Why?

How do you account for the formation of ethane during chlorination of methane?

What are hybridisation states of each carbon atom in the following compounds ?

(i) CH₂=C=O,

(ii) CH₃CH=CH₂,

(iii) (CH₃)₂CO,

(iv) CH₂=CHCN,

(v) C₆H₆

What will be the minimum pressure required to compress 500 dm³ of air at 1 bar to 200 dm³ at 30°C?

What are the common physical and chemical features of alkali metals?

Calculate the molecular mass of the following:
(i) H₂O
(ii) CO₂
(iii) CH₄

What is the basic theme of organisation in the periodic table?

Explain the formation of a chemical bond.

Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only.

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?

Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

What are the harmful effects of photochemical smog and how can they be controlled?

How will you convert benzene into

(i) p - nitrobromobenzene

(ii) m - nitrochlorobenzene

(iii) p - nitrotoluene

(iv) acetophenone?

Find energy of each of the photons which

(i) correspond to light of frequency 3× 1015 Hz.

(ii) have wavelength of 0.50 Å.

Is demineralised or distilled water useful for drinking purposes? If not, how can it be made useful?

If the position of the electron is measured within an accuracy of + 0.002 nm, calculate the uncertainty in the momentum of the electron. Suppose the momentum of the electron is h/4π_m × 0.05 nm, is there any problem in defining this value.

Compare the structures of H₂O and H₂O₂.

What happens when

(a) Borax is heated strongly,

(b) Boric acid is added to water,

(c) Aluminium is treated with dilute NaOH,

(d) BF₃ is reacted with ammonia?

Discuss the general characteristics and gradation in properties of alkaline earth metals.

Write bond line formulas for : Isopropyl alcohol, 2,3-Dimethyl butanal, Heptan-4- one.

Addition of HBr to propene yields 2-bromopropane, while in the presence of benzoyl peroxide, the same reaction yields 1-bromopropane. Explain and give mechanism.