-a5 pH=-log1o[H3O'(ag]=-log1o(0.115)=0.94 The second dissociation is HSO3 (ag)+H2OSO3(ag)+H3O(ag) K-SO,HO'=6.3x10 For which [HSO,(am】 But from the first dissociation.[HO(a]=[HSO;(agl.so [SO3(l=K2 =6.3x 105 M 4. Balance the following REDOX reaction in a basic solution: For the oxidation reaction Se032agl→Se0raml Se0,oam+H0→se0am SeO: (a )+H0→Se0,am+2H SeOj(oa)+H20 SeOi(aa)+2 H+2 e For the reduction reaction: Clg→2Ctam Cl2g+2e→2Cfag Adding the two half reactions together: SeO3"(ag)Cl2g)+H2O SeOi(ag)+2 Cr(ag)+2 H (ag To convert to basic solution.add OH to both sides SeOs+Cl2g+H20+2 OHag SeOi(o)+2 Cr+2 H)+2 OH(a) SeO3(ag)+Cl20g)+H2O+2OH (ag)SeOi(ag)+2Cr(ag)+2 H2O) SeOs(a)+Cl2+2 OH a>SeOi(ag)+2 CTa+H2Ow 3 Thus, x = [H3O+ (aq)] = [HSO3 - (aq)] = 0.115 M [H2SO3] = 1.00 – x = 0.885 M pH = -log10[H3O+ (aq)] = -log10(0.115) = 0.94 The second dissociation is HSO3 - (aq) + H2O(l) ¤ SO3 -2 (aq) + H3O+ (aq) For which 8 )aq( 3 )aq( 3 )aq( 2 3 2a 103.6 ]HSO[ ]OH][SO[ K − − − + = ×= But from the first dissociation, [H3O+ (aq)] = [HSO3 - (aq)], so [SO3 -2 (aq)] = Ka2 = 6.3 x 10-8 M 4. Balance the following REDOX reaction in a basic solution: SeO3 -2 (aq) + Cl2(g) → SeO4 -2 (aq) + Cl- (aq) For the oxidation reaction: SeO3 -2 (aq) → SeO4 -2 (aq) SeO3 -2 (aq) + H2O → SeO4 -2 (aq) SeO3 -2 (aq) + H2O → SeO4 -2 (aq) + 2 H+ SeO3 -2 (aq) + H2O → SeO4 -2 (aq) + 2 H+ + 2 e￾For the reduction reaction: Cl2(g) → 2 Cl- (aq) Cl2(g) + 2 e- → 2 Cl- (aq) Adding the two half reactions together: SeO3 -2 (aq) + Cl2(g) + H2O → SeO4 -2 (aq) + 2 Cl- (aq)+ 2 H+ (aq) To convert to basic solution, add OH- to both sides: SeO3 -2 (aq) + Cl2(g) + H2O + 2 OH- (aq) → SeO4 -2 (aq) + 2 Cl- (aq)+ 2 H+ (aq) + 2 OH- (aq) SeO3 -2 (aq) + Cl2(g) + H2O + 2 OH- (aq) → SeO4 -2 (aq) + 2 Cl- (aq)+ 2 H2O(l) SeO3 -2 (aq) + Cl2(g) + 2 OH- (aq) → SeO4 -2 (aq) + 2 Cl- (aq)+ H2O(l)