In the reaction between warm concentrated sulfuric acid and potassium iodide 8I-(aq)+ H2SO4 (aq) + 8H+(aq) → 4I2(g) +H2S (g) +4H2O
I- is reduced
H2S is the reducing agent
H+ is reduced
H2SO4 is the oxidizing agent
The emf of the cell Zn(s) | Zn2+(1.0M)| | Pb2+(1.0M) | Pb (s) is E0pb2+/pb = -0.126VE0Zn2+Zn = -0.76V
+0.886 V
+ 0.634 V
- 0.634 V
- 0.886V
The oxidation number of Cr in Na2Cr2O7 is
+2
+6
+3
+12
The brown ring complex compound is formulated as [Fe(H2O)5 (NO)] SO4. The oxidation number of iron is
+1
0
The standard electrode potential of Cu / Cu2+ electrode is - 0.34 V.Its corresponding reaction is
Cu → Cu2+ + 2e -
Cu2+ +2e- → Cu
Reduction involves:
Gain of electrons
Loss of electrons
Decrease in the valency of negative part
Increase in oxidation number
Given:E0Zn2+/ Zn = -0.76VE0Ag+/Ag = 0.80VWhich of the following reactions actually takes place?
Zn(s) + 2Ag+ (aq) → Zn2+ (aq)+ 2Ag(s)
Zn2+ (aq) + 2Ag(s) → Zn(s) + 2Ag+(aq)
Zn (s) + Ag(s) → Zn2+ (aq) + Ag+(aq)
Zn2+ (aq) + Ag(s) → Ag+ (aq) + Zn+ (aq)
The oxidising agent in the following reactions is H2O2 + O3 → H2O +2O2
H2O2
O3
Both H2O2 and O3
Unpredictable
3Br2 + 6NaOH → NaBrO3 + 5NaBr + 3H2O in this reaction, the element which loses as well as gains electron is
Na
Br
O
H
Given E0Zn2+= -0.76 V, E0Cr3+/Cr= - 0.74 V, E0H+/H2=0 & E0Fe3+/Fe2+ = +0.77VWhich is the strongest reducing agent?
Zn
Cr
H2
Fe 3+
