In the two cited molecules, Br is more electronegative than I. Therefore, the O-H bond in HBrO3is weaker than the O-H bond in HIO3, so HBrO3is the strongeracid. b. HNO2, HNO3HNO3> HNO2.Four electronegative groups in HNO3, vs three in HNO2, result in a more polar O-H bond, and therefore a weaker O-H bond.KaHNO3largeHNO27.2 x 10-4c. HOCl, HOIHOCl > HOI. Cl is more electronegative than I. This results in a more polar O-H bond, and therefore a weaker O-H bond.d. H3PO4, H3PO3H3PO4> H3PO3.H3PO4has 5 electronegative groups separating the O-H as compared to the 4 electronegative groups in H3PO3. This makes the O-H bond in H3PO4more polar and therefore weaker. Chem 162-2015 Chapter 17 Tro Acid-Base Equilibria 19
STRENGTHS OF CARBOXYLIC ACIDSCH3CH2COOHPropanoic acidKa= 1.3 x 10-5I-CH2CH2COOHCl-CH2CH2COOHCH3CHClCOOHCH3CCl2COOH3-Iodopropanoic acid3-Chloropropanoic acid2-Chloropropanoic acid 2,2-Dichloropropanoic acidKa= 8.3 x 10-5Ka= 1.0 x 10-4Ka= 1.4 x 10-3Ka= 8.7 x 10-3Chem 162-2015 Chapter 17 Tro Acid-Base Equilibria 20
STRENGTHS OF AMINES AS BASESRecall that a Bronsted-Lowry base is anything that tends to react with a proton.