KMno4 solution can be standardized against As2O3. a .2661g sample of  As2O3 was dissoved in acidic solution            ( As2O3 +2h2o=2H3AsO3)         If 38.22ml of KmnO4 solution was required to react with this amt of  As2O3 , what is the M of the KMnO4 solution?                          (2MnO4- + 6H++5H3ASO3=2 Mn^2+ +5H3AsO4+ 3H2O)     [i dont understand how to translate the  As2O3  into kmno4 because there is no KMnO4 in the second reaction]

 KMnO4 is written as Mno4- and you have to see relation between Mno4- and As2O3
set up ratio table like this
g of As2O3 ---->moles of As2O3 -----> moles of H3AsO3- ------>moles of MnO4-
    =0.2661g As2O3    x   1mole As2O3/ 197.84gAs2O3    X  2moles of H3AsO3 /1mole As2O3
      X 2 moles of  MnO4-/5 moles of H3ASO3 =1.08*10^-3 moles
now molarity = moles of MnO4- / volume in L = 1.08*10^-3 moles /38.22 *10^-3L= 0.028M