德克萨斯州立大学化学与生物化学系：《分析化学》科学讲座_酸碱平衡 Acid-Base Equilibria

Acid-Base Equilibria Ji Chang Department of Chemistry and Biochemistry Texas state University

Acid-Base Equilibria Base Equilibria Ji Chang Department of Chemistry and Biochemistry Texas State University

Arrhenius definitions e Arrhenius acids are substances which when dissolved in water. increase the h+ concentration HCI is an Hcl(g)→Hao+Cao Arrhenius acid O Arrhenius bases are substances which. when dissolved in water increase the oh concentration Naoh is an NaOH→Nata+OH (ag) Arrhenius base

Arrhenius Definitions Arrhenius Definitions Arrhenius acids are substances which, when Arrhenius acids are substances which, when dissolved in water, increase the H dissolved in water, increase the H + concentration. concentration. HCl(g) → H + (aq) + Cl − (aq) Arrhenius bases are substances which, when Arrhenius bases are substances which, when dissolved in water, increase the OH dissolved in water, increase the OH − concentration. concentration. NaOH(s) → Na + (aq) + OH − (aq) HCl is an Arrhenius acid. NaOH is an Arrhenius base

H+ in water H ClH+O H H H H-0-H+H-O H Hydronium Ion H H

H+ in Water in Water H O H H H O H+ H + Hydronium Ion

Bronsted-Lowry Definitions eA Bronsted-Lowry acid is any substance capable of donating a proton eA Bronsted-Lowry base is any substance that is capable of accepting a proton

Bronsted-Lowry Definitions A Bronsted A Bronsted -Lowry acid is any substance capable Lowry acid is any substance capable of donating a proton. of donating a proton. A Bronsted A Bronsted -Lowry base is any substance that is Lowry base is any substance that is capable of accepting a proton. capable of accepting a proton

Acid HCI→I++C HAc H+ Ac NH4→H+NH3 HCO3,H CO3 HPO2→H+PO43 Fe(H,o)23+- >H+ Fe(H,o)5(oh)2+ Base Ac+→HAc NH3+Ⅲ→NH4+ PO3+H+→HPO42

Acid HCl → H+ + Cl￾HAc → H+ + Ac￾NH4+ → H+ + NH3 HCO3- → H+ + CO32- HPO42- → H+ + PO43- Fe(H2O)63+ → H+ + Fe(H2O)5(OH)2+ Base Ac- + H+ → HAc NH3 + H+ → NH4+ PO43- + H+ → HPO42-

Example ●NH2(a)+H2O0→>NHag)+OH(ao BL BL base ac ●HC2O4(a0+CO32 CO 24(aq) Hco 3(aq) BL BL acid base e NH4*(ag+ CN(ag)2 NH3(ag)+ HCN BL BL acid base

Example Example NH2−(aq) + H2O(l) → NH3(aq) + OH−(aq) HC2O4−(aq) + CO32-(aq) ⇄ C2O42-(aq) + HCO3−(aq) NH4+(aq) + CN−(aq) ⇄ NH3(aq) + HCN(aq) BL base BL base BL base BL acid BL acid BL acid

Conjugate Acid-Base Pairs BL 4(aq)+ (ag) BP(ag)+ HCN bL(aq) acid base base acid NH4+ and NH3 are called a conjugate acid-base pair, as are cnˉ and hcn A conjugate acid-base pair is an acid and a base that differ only by a proton

Conjugate Acid Conjugate Acid -Base Pairs NH 4 + (aq) + CN − (aq) ⇄ NH3(aq) + HCN(aq) BL base BL acid BL base BL acid • NH 4 + and NH 3 are called a conjugate acid-base pair, as are CN − and HCN. • A conjugate acid-base pair is an acid and a base that differ only by a proton

Example Determine the conjugate base of HCIO4 CIO H2SO4 HSO 4 HCI Subtract H* CI- HCO3 CO3

Example Determine the conjugate base of: HClO4 H2SO4 HCl HCO3− ClO4− HSO4− Cl− CO32- Subtract H+

Example Determine the conjugate acid of CN HCN HCO3 Add H H2CO3 SO4 HSO4

Example Determine the conjugate acid of: CN− H2O HCO3− SO42- HCN H3O+ H2CO3 HSO4− Add H+

Amphiprotic e Substances that can act either as an acid or as a base are called amphiprotic HCO3+ H2O 2 H3O* CO 3 HCO3+ H2O 2 H2CO3+OH- HCO is an amphiprotic substance

Amphiprotic Substances that can act either as an Substances that can act either as an acid or as a base are called acid or as a base are called amphiprotic. amphiprotic. HCO 3 − + H 2O ⇄ H 3 O + + CO 3 2 - HCO 3 − + H 2O ⇄ H 2CO 3 + OH − HCO 3 − is an amphiprotic substance