Calculate the oxidation number of Cr in [Cr (H2O)6]3+ ion.
H2O is a neutral molecule O.N of H2O = 0
Write the oxidation number of Cr above its symbol and that of H2O above its formula,
Identify the correct statements with reference to the given reaction.
P4 + 30H– + 3H20→ PH3 + 3H2 P0–2
(a) Phosphorus is undergoing reduction only.
(b) Phosphorus is undergoing oxidation only.
(c) Phosphorus is undergoing oxidation as well as reduction.
(d) Hydrogen is undergoing neither oxidation nor reduction
While sulphur dioxide and hydrogen peroxide can act as an oxidising as well as reducing agents in their reactions, ozone and nitric acid act only as oxidants. Why?
Arrange the following metals in the order in which they displace each other from the solution of their salts.Al, Cu, Fe, Mg and Zn.
Calculate the oxidation number of phosphorus in the following species.
(a) HPO32- and (b) P043-
In Ostwald’s process for the manufacture of nitric add, the first step involves the oxidation of ammonia gas by oxygen gas to give nitric oxide gas and steam. What is the maximum wight of nitric oxide that can be obtained starting only with 10.0 g of ammonia and 20.0 g of oxygen?
Which of the following electrodes will act as anodes, when connected to Standard Hydrogen Electrode?
(a) A13-/A1; E °= -1.66 V
(b) Fe2+ /Fe; E °= -0.44 V
(c) Cu2+/ Cu E °=34 V
(d) F2(g)/2F–(aq) E °= 2.87 V
Which of the following statement(s) is/are not true about the following decomposition reaction?
2KCIO3 →2KC1 + 302
(a) Potassium is undergoing oxidation.
(b) Chlorine is undergoing oxidation.
(c) Oxygen is reduced.
(d) None of the species are undergoing oxidation or reduction.
Nitric acid is an oxidizing agent and reacts with PbO but it does not react with Pb02. Explain why?
Identify the redox reactions out of the following reactions and identify the oxidizing and reducing agents in them
Predict the products of electrolysis in each of the folloxving:
(i) An aqueous solution of AgNO3 with silver electrodes.
(ii) An aqueous solution of silver nitrate with platinum electrodes.
(iii) A dilute solution of H2S04with platinum electrodes.
(iv) An aqueous solution of CuCl2 with platinum electrodes.
What is standard hydrogen electrode? For what purpose it is used? What are signs of oxidation potential and reduction potential decided by using SHE (Standard hydrogen electrode)?
(a) Balance the following equation by oxidation number method or by ion electron (half reaction) method.
In which of the following compounds, an element exhibits two different oxidation states.
(a) NH2OH
(b) NH4NO3
(c) N2H4
(d) N3H
Fluorine reacts with ice and results in the change:
H20(S) + F2 (g) ——-> HF(g) + HOF(g)
Justify that this reaction is a redox reaction.
Identify the substance oxidised, reduced, oxidising agent and reducing agent for each of the following reactions.
Thiosulphate reacts differently with iodine and bromine in the reactions given below:
2S2032_ + I2→S4062- + 2I–
S2032- + 2Br2 + 5H20 →2S042- + 4Br– + 10H+
Which of the following statements justifies the above dual behaviour of thiosulphate?
(a) Bromine is a stronger oxidant than iodine.
(b) Bromine is a weaker oxidant than iodine.
(c) Thiosulphate undergoes oxidation by bromine and reduction by iodine in these reactions.
(d) Bromine undergoes oxidation and iodine undergoes reduction in these reactions.
Identify the correct statement(s) in relation to the following reaction:
Zn + 2HCl → ZnCl2 + H2
(a) Zinc is acting as an oxidant.
(b) Chlorine is acting as a reductant.
(c) Hydrogen ion is acting as an oxidant.
(d) Zinc is acting as a reductant.
Justify that the following reactions are redox reactions:
(a) CuO(s) + H2(g) —–> Cu(s) + H20(g)
(b) Fe2O3(s) +3CO(g) —-> 2Fe(s) + 3CO2(g)
(c) 4BCl3(g) +3LiAlH4(s) ——> 2B2H6(g) + 3LiCl(s) + 3AlCl3(s)
(d) 2K(s) +F2(g)——> 2K+F–(s)
Identify the substance oxidised, reduced, oxidising agent and reducing agent for each of the following reactions.
Balance the following redox reactions by ion-electron method.
(a) MnO4–(aq) +I–(aq) ———>Mn02(s) + I2 (s) (in basic medium)
(b) MnO4–(aq) + S02(g) ——-> Mn2+(aq) +H2S04–(in acidic solution)
(c) H2O2(aq) + Fe2+(aq) ———-> Fe3+(aq) + H2O(l) (in acidic solution)
(d) Cr2O72- (aq) + S02 (g)——> Cr3+ (aq) + SO42-(aq) (in acidic solution)
What is meant by electrochemical series? What are characteristics of electrochemical series?
E ° values of some redox complexes are given below. On the basis of these values choose the correct option.
E ° values: Br2/Br– = +1.90; Ag+/Ag(s) = +0.80 Cu2+/Cu(s) = +0.34; I2(s)/I– = +0.54 V
(a) Cu will reduce Br–
(b) Cu will reduce Ag
(c) Cu will reduce I–
(d) Cu will reduce Br2
PbO and Pb02 react with HC1 according to following chemical equations:
2PbO + 4HCl → 2PbCl2 + 2H20
Pb02 + 4HC1 → PbCl2 + Cl2 + 2H20
Why do these compounds differ in their reactivity?
(a)Give two important functions of salt bridge.
(b)Balance the following equation by oxidation number method:
Fe2+ + Cr2O72- + H+ ———> Fe3+ + Cr3+ +H2O
The largest oxidation number exhibited by an element depends on its outer electronic configuration. With which of the following outer electronic configurations the element will exhibit largest oxidation number?
(a) 3d14s2
(b) 3d2 4s2
(c) 3d54s1
(d) 3d54s2
Which of the following elements does not show disproportionation tendency?
(a) Cl
(b) Br
(c) F
(d) I
The reaction Cl2(g) + 20H–(aq)→ Cl0–(aq) + Cl–(aq) + H20(l) represents the process of bleaching. Identify and name the species that bleaches the substances due to its oxidizing action.
The compound AgF2 is unstable. However, if formed, the compound acts as a very strong oxidising agent. Why?
Justify-giving reactions that among halogens, fluorine is the best oxidant and among hydrohalic compounds, hydroiodic add is the best reductant.
Consider the elements: Cs, Ne, I, F
(a) Identify the element that exhibits -ve oxidation state.
(b) Identify the element that exhibits +ve oxidation state.
(c) Identify the element that exhibits both +ve and -ve oxidation states.
(d) Identify the element which neither exhibits -ve nor +ve oxidation state.
Consider a voltaic cell constructed with the following substances:
(a) Which substances are oxidised and reduced in this cell?
(b) Which are the negative and positive electrode?
Write the O.N of all the atoms for the following well known oxidants?
(i) KMnO4 (ii) K2Cr2O7 (iii) KClO4
(a) Arrange the following in order of increasing O.N of iodine:
I2, HI, HIO2, KIO3, ICl.
(b) Identify the oxidant and reductant in the following redox reaction:
2K2Mn04 + Cl2 ———–> 2KCl + 2KMnO4
Identify disproportionation reaction
(a) CH4 + 202 → C02 + 2H20
(b) CH4 + 4C12 → CC14 + 4HCl
(c) 2F2 + 20H–→2F– + OF2 + H20
(d) 2N02 + 20H– → N02 + NO–3 + H20
The exhibition of various oxidation states by an element is also related to the outer orbital electronic configuration of its atom. Atom(s) having which of the following outermost electronic configurations will exhibit more than one oxidation state in its/their compounds.
(a) 3s1
(b) 3dl4s2
(c) 3d24s2
(d) 3s23p3
