Table 10.2: pKa and pKb values at 25 °C for some common weak acids and their con
ID: 694074 • Letter: T
Question
Table 10.2: pKa and pKb values at 25 °C for some common weak acids and their conjugate bases pKaConjugate base 0.20 FCCOo 0.66 Cl3 CCoo 1.23 HOOCCOO 1.30 CI2HCCOO 1.77 HS03 1.92 So- 1.95 CIO2 2.12 H2P0 2.87 CIH2CCOO 2.90 BrH2CCOO 3.08 C2HoCOO 3.13 C3H5O(COOH)2COO dihydrogen citrate ion10.87 Acid name trifluoroacetic acid trichloroacetic acid oxalic acid dichloroacetic acid Acid formula F3CCOOH Cl CCOOH HOOCCOOH CI2HCCOOH Conjugate base name trifluoroacetate ion trichloroacetate ion hydrogen oxalate ion dichloroacetate ion hydrogen sulfite ion sulfate ion chlorite ion dihydrogen phosphate ion chloroacetate ion bromoacetate ion lactate ion 13.80 13.34 12.70 12.23 12.08 sulfurous acid hydrogen sulfate ion chlorous acid phosphoric acid chloroacetic acid bromoacetic acid lactic acid citric acid hydrofluoric acid nitrous acid acetylsalicylic aci formic acid ascorbic acid hydrogen oxalate ion benzoic acid HCIO H3PO CIH2CCOOH BrH2CCOOH 11.88 10.92 C3Hs O(COOH)3 10.80 10.63 10.52 fluoride ion nitrite ion acetvlsalicylate ion formate ion ascorbate ion oxalate ion benzoate ion phenylamine (aniline) HNO 3.37 NO2 3.48 CH,O2COo 3.75 HCOO 4.10CH,OCOO 4.19ooccoO 4.20 C6H5COO HCOOH 9.81 C&H;, COOH phenylammonium ionHsNH3 4.63 CH,NH2 9.37Explanation / Answer
1) 7.27×10-5 M propanoic acid
Ka = 1.3 x 10^-5
[H+] = sqrt (Ka x C)
= sqrt (1.3 x 10^-5 x 7.27 x 10^-5)
= 3.07 x 10^-5 M
percent ionisation = ( [H+] / initial concentration ) x 100
= [ 3.07 x 10^-5 / (7.27 x 10^-5) ] x 100
= 42.3 %
it is more than 5% so it is not valid . so answer NO
2) 3.52×10-4 M sulfurous acid
similarly by solving this above problem . it is also not valid . NO
3) 9.14×10-2 M nitrous acid
answer : NO
4) 9.28×10-2 M pyridinium ion
answer : YES
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