`I_(2(aq))+2S_(2)O_(3(aq))^(-2) to 2I_((aq))^(-)+S_(4)O_(6(aq))^(2-)`
For the above titrimetric reaction how is the end point determined?

H_(2)SO_(4(aq)) + 2KOH_((aq)) rarr K_(2)SO_(4(aq)) + 2H_(2)O_((l)), Delta H for the above reaction is

H_((aq))^(+) + OH_((aq))^(-) rarr H_(2)O_((l)) , Delta H = -ve and Delta G= -ve then the reaction is

i) H_3PO_(4(aq)) iff H^ _(aq)+ H_2PO_(4(aq))^- ii) H_2PO_(4(aq))^- iff H^ +(aq)+ H_2PO_(4(aq))^(2-) . iii) H_2PO_(4(aq))^(2-) iff H^ +(aq)+ PO_(4(aq))^(3-) . The equilibrium constantsfor the above reactions at a certain temperature are K_1, K_2 and K_3 respectively. The equilibrium constant for the reaction. H_3PO_4(aq) iff 3H^ +(aq)+ PO_(4(aq))^(3-) in terms K_1, K_2 and K_3 is

H_(2)SO_(4)(aq)+2NaOH_((aq))to Na_(2)SO_(4)(aq) +2H_(2)O_((l)) . Suggest the hest of this reaction.

For the reaction 2H_(2)O_((l)) rarr H_(3)O_((aq))^(+) + OH_((aq))^(-) , the value of Delta H is