Question

1. Provide the oxidation number for each of the underlined elements in following compounds or ions: (6) a) H3AsO3 b) d) H4P207 C202² KCIO4 N2H4 2. Which one of the following is not a oxidation-reduction reaction? (2) A) 2H2(g) + O2(g) → 2H2O(1) B) Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) C) H2O(l) + NH3(g) → NH(aq) + OH(aq) D) FeSO4(aq) + K2Cr2OH(aq) + 7H2SO4(aq) → Cr2(SO4)3(aq) + 3Fe2(SO4)3(aq) + K2SO4(aq) + 7H2O(1) E) Cl2(g) +2KBr(aq) + Bra(l) + 2KCl(aq) (8) 3. For each of the following reactants, identify: the oxidizing agent, the reducing agent, the substance oxidized and the substance reduced. a) Cu2+ (aq) + Zn (s) Cu + Zn²+ (aq) Substance oxidized Oxidizing agent Substance reduced Reducing agent b) Cl2(g) + 2 Na (s) 2 Nat (aq) + 2Cl(aq) Substance oxidized Oxidizing agent Substance reduced Reducing agent

Answer 1

Das suppose the oxidation number of As in H₂ ASOz į x Total charge of the molecule =o. Charge of t į (+1) and of oxygen 3 +2 - 6= 0 = 6-3 =3 oxidation no. of AS b (+3). A1 x -2 6) Toks . Hy 07 charge of H = +1 Total charge = 0. no=-2 [4x(+1) +2x + 7 =(-2)]=0 or ax= 10 [ 2x is for 2'l' or r= 5 atoms] c) kalon Total charge o charge of k= +1 1 » d = -2 1+2-8=0. x = +7 oxdi oxidation state of a = +7

d) Sou- charge of 'o = -2 suppose charge of carbon = 'x' as a carbon atom, so total charge = 2x Total charge = -2 i 2x + 4x(-2) = -2 oy, 2x – 8--2 oxidation state of carbon į (+3). e) N2H4 charge of t = + suppose oxidation total =22 State of 'N' ; x Total charge of atom ao 2x+4=0. x = -2 state į (-2) oxidation $) 12 suppose - I is a oxidation 2x=0 or state of x=0.

i oxidation state of I=0. 27 In a oxidation - reduction neaction the change in the oxidation number occurs. If the theane reaction is no is non redox transfer of electrons. +2 A) 242(g) + O2(g) → 2H6W change is oxidation number occurs. so redox reaction. By Zu (3) + H₂SO4 (a) → Zn 504 (aq) + Hy Lg Change y there, oxidation no. changes, so redox reaction. to + 18) NH 4 (ar) + 8 - No change in oxidation no. , so it is not a oxidation reduction reaction. of 6 resou (aq) + 42080 (99)+ 7 H₂SO4 (92) → om (soy), + 3Fe (sou), (09) + 1,504@r) +7H₂O + 7 +3, in oxidation no. so redox reaction

E cůz (9) + 2 KBr (aq) → Brz (1) + akcê (ar) Here also change in oxidation no. So redox reaction. Ey is not a oxidation reduction reaction 3) oxidation is a procedure where loss of electron takes place. and reduction ij a procedure where gain of electron takes place. and an oxidising agent oxidizes the other reagent and reduces itself. and an reducing agent reduces the other reagent and oxidises itself. suppose in a chemical reaction - A+Bo - A + B Here A loses the electron. so AA® ý oxidation and A ý the reducing agent as it reduces Bo to B' and vice - versa ie B B ý reduction

and Be oxidisiting agent. a cu 2+ (aq) + 2n(s) aut 202 + (ar) cu 2t cure gain of electron so reduction bu 20 - 20 the loss of electron so oxidation. oxidising agent = cult can). reducing = 20 (3) cu 2t is reduced to cu and an ij oxidised to an 2+ . 6) & 19 + 2Na (3) - 2 Nat (an) + See on + Duranochning + 2Na 2 NG ) +20 (on) od 24-ze gain of electron, so reduction. 2NG - 2 Nat the loss of electron, so oxidaton. oxidising agent - cz. reducing " = Na Na s oxidised to wat and cle is reduced to cê.