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O solutie apoasa de acid formic si acid oxalic cu masa de 500g, in care cei doi acizi se afla in raport molar 1:3 este neutralizata de 262,5 g solutie de NaOH 32%.Concentratiile procentuale ale celor 2 acizi in solutia initiala...

Răspuns :

fiind in raport molar de 1:3 avem a moli din fiecare acid

HCOOH = ac. formic , M = 46 g/mol

HOOC-COOH = ac oxalic , M = 90 g/mol

ms = 500 g solutie de acizi

ms = 262,5 g sol NaOH

c = 32% , stim ca c% = mdx100/ms

=> md = msxc/100 = 262,5x32/100

= 83,84 g NaOH => 2,096 moli NaOH

  1a moli      b moli

HCOOH + NaOH => HCOONa + 1/2H2

   1                1

 3a moli              c moli

HOOC-COOH + NaOH => NaOOC-COONa + H2

    1                          1

=> b = 1a  ,  c = 3a

=> 1a + 3a = 2,096 moli NaOH

=> a = 0,524 moli NaOH

=> 1ax46 = 24,10 g ac formic

=> 3ax90 = 141,48 g ac. oxalic

=> c%.ac.formic = 24,10x100/500 = 4,82%

    c%.ac.oxalic = 141,48x100/500 = 28,3%