Question

1. Faceti ionizarea si scrieti constanta de aciditate pentru:
a) H2CO3;
b) H3PO4.
Multumesc!

Answer 1

a) H2CO3;

H2CO3 <==> HCO3(-) + H(+)

Ka1 = [H(+)]x[HCO3(-)]/[H2CO3]

HCO3(-) <==> CO3(-2) + H(+)

Ka2 = [H(+)]x[CO3(-2)]/[HCO3(-)]

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Ka = Ka1×Ka2, dar Ka1 >> Ka2

b) H3PO4.

H3PO4 <==> H2PO4(-) + H(+)

Ka1 = [H(+)]x[H2PO4(-)]/[H3PO4]

H2PO3(-) <==> HPO3(-2) + H(+)

Ka2 = [H(+)]x[HPO3(-2)]/[H2PO3(-)]

HPO3(-2) <==> PO3(-3) + H(+)

Ka3 = [H(+)]x[PO3(-3)]/[HPO3(-2)]

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Ka = Ka1×Ka2×Ka3, dar Ka1 > Ka2 >> Ka3