當(dāng)pH=5.00時(shí),0.20mol/L二元弱酸(H2A)溶液中,H2A的濃度為() (設(shè)H2A的pKa1=5.00,pKa2=8.00)
A.0.15mol/L B.0.10mol/L C.0.075mol/L D.0.050mol/L
A.1/10 B.10 C.1/2 D.2
A.H3PO4+H2PO4- B.H2PO4-+HPO42- C.H3PO4+HPO42- D.HPO42-+PO43-