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
(a) NaH2PO4
Let's assume oxidation number of P is x.
We know that,
Oxidation number of Na = +1
Oxidation number of H = +1
Oxidation number of O = -2
Then we have
1(+1) + 2(+1) + 1 (x) + 4(-2) = 0
⇒ 1 + 2 + x - 8 = 0
⇒ x - 5 = 0
⇒ x = + 5
Hence, oxidation number of P is +5
(b) NaHSO4
Let's assume oxidation number of S is x.
Oxidation number of Na = +1
Oxidation number of H = +1
Oxidation number of O = -2
Then we have:
1(+1) + 1(+1) + 1 (x) + 4(-2) = 0
⇒ 1 + 1 + x - 8 = 0
⇒ x-6 = 0
⇒ x = +6
Hence, oxidation number of S is +6
(c) H4P2O7
Let's assume oxidation number of P is x.
Oxidation number of H = +1
Oxidation number of O = -2
Then we have:
4(+1) + 2(x) + 7 (-2) = 0
⇒ 4 + 2x - 14 = 0
⇒ 2x - 10 = 0
⇒ 2x = +10
⇒ x = +5
Hence, Oxidation number of P is +5
(d) K2MnO4
Let's assume oxidation number of Mn is x.
Oxidation number of K = +1
Oxidation number of O = -2
Then we have:
2(+1) + 1(x) + 4 (-2) = 0
⇒ 2 + x - 8 = 0
⇒ x - 6 = 0
⇒ x = +6
Hence, Oxidation number of Mn is +6
(e) CaO2
Let's assume oxidation number of O is x.
Oxidation number of Ca = +2
Then we have:
1(+2) + 2(x) = 0
⇒ 2 + 2x = 0
⇒ 2x = -2
⇒ x = -1
Hence, Oxidation number of O is -1
(f) NaBH4
Let's assume oxidation number of B is x.
Oxidation number of Na = +1
Oxidation number of H = -1
Then we have:
1(+1) + 1(x) + 4(-1) = 0
⇒ 1 + x -4 = 0
⇒ x - 3 = 0
⇒ x = +3
Hence, Oxidation number of B is +3.
(g) H2S2O7
Let's assume oxidation number of S is x.
Oxidation number of O = -2
Oxidation number of H = +1
Then we have:
2(+1) + 2(x) + 7(-2) = 0
⇒ 2 + 2x - 14 = 0
⇒ 2x - 12 = 0
⇒ x = +6
Hence, Oxidation number of S is +6.
(h) KAl(SO4)2.12 H2O
Let's assume oxidation number of S is x.
Oxidation number of K = +1
Oxidation number of Al = +3
Oxidation number of O = -2
Oxidation number of H = +1
Then we have:
1(+1) + 1 (+3) + 2(x) + 8(-2) + 24(+1) + 12 (-2) = 0
⇒ 1 + 3 + 2x -16 +24 -24 = 0
⇒ 2x - 12 = 0
⇒ 2x = +12
⇒ x = +6
Hence, Oxidation number of S is +6.
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)
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) + 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)
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) P4(s) + OH – (aq) → PH3(g) + HPO2 – (aq)
(b) N2H4(l) + ClO3 – (aq) → NO(g) + Cl–(g)
(c) Cl2O7 (g) + H2O2(aq) → ClO – 2(aq) + O2(g) + H + (aq)
Fluorine reacts with ice and results in the change:
H2O(s) + F2(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) + C6H6O2(aq) → 2Ag(s) + 2HBr (aq) + C6H4O2(aq)
(b) HCHO(l) + 2[Ag (NH3)2]+(aq) + 3OH-(aq) → 2Ag(s) + HCOO-(aq) + 4NH3(aq) + 2H2O(l)
(c) HCHO (l) + 2Cu2+(aq) + 5 OH-(aq) → Cu2O(s) + HCOO-(aq) + 3H2O(l)
(d) N2H4(l) + 2H2O2(l) → N2(g) + 4H2O(l)
(e) Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l)
The compound AgF2 is an unstable compound. However, if formed, the compound acts as a very strong oxidizing agent. Why?
Calculate the oxidation number of sulphur, chromium and nitrogen in H2SO5, Cr2O2- 7 and NO– 3. Suggest structure of these compounds. Count for the fallacy.
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.
Explain why cations are smaller and anions larger in radii than their parent atoms?
Which of the two: OO2NCH2CH2O- or CH3CH2O- is expected to be more stable and why?
How is excessive content of CO2 responsible for global warming?
Calculate the volume occupied by 8.8 g of CO2 at 31.1°C and 1 bar pressure.
R = 0.083 bar L K–1 mol–1.
Explain the formation of H2 molecule on the basis of valence bond theory.
How do you account for the formation of ethane during chlorination of methane?
What effect does branching of an alkane chain has on its boiling point?
Kp = 0.04 atm at 899 K for the equilibrium shown below. What is the equilibrium concentration of C2H6 when it is placed in a flask at 4.0 atm pressure and allowed to come to equilibrium?
C2H6 (g) ↔ C2H4 (g) + H2 (g)
For the following equilibrium, Kc = 6.3 × 1014 at 1000 K
NO (g) + O3 (g) ↔ NO2 (g) + O2 (g)
Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is Kc, for the reverse reaction?
Calculate the hydrogen ion concentration in the following biological fluids whose pH are given below:
(a) Human muscle-fluid, 6.83
(b) Human stomach fluid, 1.2
(c) Human blood, 7.38
(d) Human saliva, 6.4.
Gud to disclose all the answers .anyway thanks