Justify that the following reactions are redox reactions:
(a) CuO(s) + H2(g) → Cu(s) + H2O(g)
(b) Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g)
(c) 4BCl3(g) + 3LiAlH4(s) → 2B2H6(g) + 3LiCl(s) + 3 AlCl3 (s)
(d) 2K(s) + F2(g) → 2K+F– (s)
(e) 4 NH3(g) + 5 O2(g) → 4NO(g) + 6H2O(g)
(a) CuO(s) + H2(g) → Cu(s) + H2O(g)
Let us write the oxidation number of each element involved in the given reaction as:
+2 -2 0 0 +1 -2
Cu O(s) + H2(g) → Cu(s) + H2 O(g)
Here, the oxidation number of Cu decreases from +2 in CuO to 0 in Cu i.e., CuO is reduced to Cu. Also, the oxidation number of H increases from 0 in H2 to +1 in H2O i.e., H2 is oxidized to H2O. Hence, this reaction is a redox reaction.
(b) Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g)
Let us write the oxidation number of each element involved in the given reaction as:
+3 -2 +2 -2 0 +4 -2
Fe2 O3(s) + 3C O(g) → 2Fe(s) + 3C O2(g)
Here, the oxidation number of Fe decreases from +3 in Fe2O3 to 0 in Fe i.e., Fe2O3 is reduced to Fe. On the other hand, the oxidation number of C increases from +2 in CO to +4 in CO2 i.e., CO is oxidized to CO2. Hence, the given reaction is a redox reaction.
(c) 4BCl3(g) + 3LiAlH4(s) → 2B2H6(g) + 3LiCl(s) + 3 AlCl3 (s)
Let us write the oxidation number of each element involved in the given reaction as:
+3 -1 +1 +3 -1 -3 +1 +1 -1 +3 -1
4B Cl3(g) + 3 Li Al H4(s) → 2B2 H6(g) + 3Li Cl(s) + 3 Al Cl3 (s)
In this reaction, the oxidation number of B decreases from +3 in BCl3 to –3 in B2H6. i.e., BCl3 is reduced to B2H6. Also, the oxidation number of H increases from –1 in LiAlH4 to +1 in B2H6 i.e., LiAlH4 is oxidized to B2H6. Hence, the given reaction is a redox reaction.
(d) 2K(s) + F2(g) → 2K+F– (s)
Let us write the oxidation number of each element involved in the given reaction as:
0 0 +1 -1
2K(s) + F2(g) → 2K+ F– (s)
In this reaction, the oxidation number of K increases from 0 in K to +1 in KF i.e., K is oxidized to KF. On the other hand, the oxidation number of F decreases from 0 in F2 to – 1 in KF i.e., F2 is reduced to KF.
Hence, the above reaction is a redox reaction.
(e) 4 NH3(g) + 5 O2(g) → 4NO(g) + 6H2O(g)
Let us write the oxidation number of each element involved in the given reaction as:
-3 +1 0 +2 -2 +1 -2
4 N H3(g) + 5 O2(g) → 4N O(g) + 6H2 O(g)
Here, the oxidation number of N increases from –3 in NH3 to +2 in NO. On the other hand, the oxidation number of O2 decreases from 0 in O2 to –2 in NO and H2O i.e., O2 is reduced. Hence, the given reaction is a redox reaction.
Popular Questions of Class 11 Chemistry
- Q:-
The mass of an electron is 9.1 × 10–31 kg. If its K.E. is 3.0 × 10–25 J, calculate its wavelength.
- Q:-
Calculate the amount of carbon dioxide that could be produced when
(i) 1 mole of carbon is burnt in air.
(ii) 1 mole of carbon is burnt in 16 g of dioxygen.
(iii) 2 moles of carbon are burnt in 16 g of dioxygen.
- Q:-
Calculate the wavelength of an electron moving with a velocity of 2.05 × 107 ms–1.
- Q:-
Balance the following redox reactions by ion – electron method :
(a) MnO4 – (aq) + I – (aq) → MnO2 (s) + I2(s) (in basic medium)
(b) MnO4 – (aq) + SO2 (g) → Mn2+ (aq) + HSO4– (aq) (in acidic solution)
(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
(d) Cr2O7 2– + SO2(g) → Cr3+ (aq) + SO42– (aq) (in acidic solution)
- Q:-
In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?
- Q:-
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
- Q:-
In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.
(i) 300 atoms of A + 200 molecules of B
(ii) 2 mol A + 3 mol B
(iii) 100 atoms of A + 100 molecules of B
(iv) 5 mol A + 2.5 mol B
(v) 2.5 mol A + 5 mol B
- Q:-
At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?
- Q:-
Which one of the following will have largest number of atoms?
(i) 1 g Au (s)
(ii) 1 g Na (s)
(iii) 1 g Li (s)
(iv) 1 g of Cl2(g)
- Q:-
Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?
Recently Viewed Questions of Class 11 Chemistry
- Q:-
An aqueous solution of borax is
(a) neutral (b) amphoteric (c) basic (d) acidic
- Q:-
How many significant figures are present in the following?
(i) 0.0025
(ii) 208
(iii) 5005
(iv) 126,000
(v) 500.0
(vi) 2.0034 - Q:-
The following data are obtained when dinitrogen and dioxygen react together to form different compounds:
Mass of dinitrogen Mass of dioxygen
(i) 14 g 16 g
(ii) 14 g 32 g
(iii) 28 g 32 g
(iv) 28 g 80 g
(a) Which law of chemical combination is obeyed by the above experimental data?Give its statement.
(b) Fill in the blanks in the following conversions:
(i) 1 km = ...................... mm = ...................... pm
(ii) 1 mg = ...................... kg = ...................... ng
(iii) 1 mL = ...................... L = ...................... dm3
- Q:-
The ionization constant of dimethylamine is 5.4 x 10-4. Calculate its degree of ionization in its 0.02 M solution. What percentage of dimethylamine is ionized if the solution is also 0.1 M in NaOH?
- Q:-
Consider the reactions:
(a) H3PO2(aq) + 4 AgNO3(aq) + 2 H2O(l) → H3PO4(aq) + 4Ag(s) + 4HNO3(aq)
(b) H3PO2(aq) + 2CuSO4(aq) + 2 H2O(l) → H3PO4(aq) + 2Cu(s) + H2SO4(aq)
(c) C6H5CHO(l) + 2 [Ag (NH3)2]+(aq) + 3OH-(aq) → C6H5COO-(aq) + 2Ag(s) + 4NH3(aq) + 2 H2O(l)
(d) C6H5CHO(l) + 2Cu2+(aq) + 5OH-(aq) → No change observed.
What inference do you draw about the behaviour of Ag+and Cu2+from these reactions?
- Q:-
One mole of H2O and one mole of CO are taken in 10 L vessel and heated to 725 K. At equilibrium 40% of water (by mass) reacts with CO according to the equation,
H2O (g) + CO (g) ↔ H2 (g) + CO2 (g)
Calculate the equilibrium constant for the reaction.
- Q:-
For the reaction at 298 K,
2A + B → C
ΔH = 400 kJ mol-1and ΔS = 0.2 kJ K-1mol-1
At what temperature will the reaction become spontaneous considering ΔH and ΔS to be constant over the temperature range?
- Q:-
For the reaction, 2Cl(g) → Cl2(g),what are the signs of ΔH and ΔS ?
- Q:-
The reaction,
CO(g) + 3H2(g) ↔ CH4(g) + H2O(g)
is at equilibrium at 1300 K in a 1L flask. It also contain 0.30 mol of CO, 0.10 mol of H2 and 0.02 mol of H2O and an unknown amount of CH4 in the flask. Determine the concentration of CH4 in the mixture. The equilibrium constant, Kc for the reaction at the given temperature is 3.90.
- Q:-
Describe the structure of the common form of ice.
1 Comment(s) on this Question
Thanks ...it's better way to check nd get the answers of NCERT
- NCERT Chapter