Question

Find the calculated pH of the following. Please show the work!!

0.1 M (NH₄)₂C₂O4

0.1 M NaC₂H₃O₂

0.1 M NaH₂PO₄

0.1 M Na₂HPO₄

0.1 M Na₃PO₄

Answer 1

0.1 M (NH4)2C2O4 - salt of weakacid,weakbase

   pH = 7+1/2(pka-pkb)

pka2 0f h2c2o4 = 4.27

   pkb og NH3 = 4.74

pH = 7+1/2(4.27-4.74)

     = 6.765

0.1 M NaC2H3O2 - salt of weak acid,strong base = basic

pH = 7+1/2(pka+logC)

     = 7+1/2(4.74+log0.1)

     = 8.87

0.1 M NaH2PO4 , salt of weak acid,strong base = basic

pH = 7+1/2(pka+logC)

pka1 of H3PO4 = 2.15

     = 7+1/2(2.15+log0.1)

    = 7.575

0.1 M Na2HPO4

salt of weak acid,strong base = basic

pH = 7+1/2(pka+logC)

pka2 of H3PO4 = 7.2

     = 7+1/2(7.2+log0.1)

     = 10.1

0.1 M Na3PO4

salt of weak acid,strong base = basic

pH = 7+1/2(pka+logC)

pka3 of H3PO4 = 12.15

     = 7+1/2(12.15+log0.1)

     = 12.575