42. 亞硫酸 H2SO3 為一雙質子酸,其 Ka1 = 1.3×10-2,Ka2 = 6.3×10-8,現有 0.1M 亞硫酸溶液,請問下列者正確?
(A) [H3O+ ] = 0.1M
(B) [H3O+ ] = 0.13M
(C) [H3O+ ] = 0.2M
(D) [HSO3─ ] = 0.013M
(E) [SO32─ ] = 6.3×10─8M
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統計: A(8), B(12), C(8), D(13), E(118) #1975395
統計: A(8), B(12), C(8), D(13), E(118) #1975395
詳解 (共 4 筆)
#4927932
- [H+] = [H3O+] = 第一次解離的氫離子濃度( 第二次的太小,可忽略 )
[H+] = [H3O+] =√(c Ka1) = √(0.1*1.3*10-2) = 0.036 - [HSO3-] = [H+] = 0.036
- 弱酸多段解離時,第二段解離的產物濃度,會剛好等於Ka2:[SO32-] = Ka2 = 6.3×10-8M
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#5364140
c跟Ka1相差得不夠多,不能用公式算[H+]
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