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Acids: Concentration vs. Strength. CONCENTRATED. DILUTE. H + A - H + A - H + A - H + A - HA A - H + A - H + A - H + A - H + A - H + A - HA H + A - H + A - H + A - A - H + A - H + A - H + A - H + A - H +
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Acids: Concentration vs. Strength CONCENTRATED DILUTE H+ A- H+ A- H+ A- H+ A-HA A- H+ A- H+ A- H+ A- H+ A - H+ A- HA H+ A- H+ A- H+ A- A- H+ A- H+ A- H+ A- H+ A- H+ H+ A - H + A - H + A -HA H + A - A- H+ A- H+ A- H+ A- H+ A– H+ A- H+ A- H+ A- H+ A- H+ A- H+ A- H+ A- H+ A- H+ A- HA A- H+ A- H+ A- H+ A- H+ H+ A - H+ A - HA A - H+ A - H+ A – H+ A - H+ A - H+ A - HA H+ A - H+ A - H+ A - H+ STRONG ACIDS Dissociate nearly 100% HA H1+ + A- WEAK ACIDS Dissociate very little HA H1+ + A- STRONG HA HA H+ A- HA HA HA HA HA HA HA HA H+ A- H+ A- HA HA HA HA HA HA HA H+ A- HA HA HA HA HA HA H+A- HA HA H+ A- HA HA HA HA HA HA HA HA H+A- HA HA H+ A- HA HA HA HA HA HA HA H+ A- HA HA HA HA HA HA HA HA HA HA H+ A - HA HA HA HA H + A – HA H + A – HA HA WEAK
Comparison of Strong and Weak Acids Reversibility of reaction Ions existing when acid, HA, dissociates in H2O Type of acid, HA Ka value Not reversible H+ and A-, only. No HA present. Ka value very large Strong Weak reversible Ka is small H+, A-, and HA HA(aq) + H2O(l) H3O+(aq) + A-(aq) The equilibrium expression for the reaction is [H3O+] [A-] Note: H3O+ = H+ Ka = [HA]
Strong vs. Weak Acid Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 508
Concentrated vs. Dilute 0.3 M HCl 10.0 M CH3COOH Dilute, strong acid Concentrated, weak acid 2.0 M HCl Concentrated, strong acid OR Dilute, strong, acid 12.0 M HCl Concentrated, strong acid
Naming Acids Anion Acid _________ ide (chloride, Cl1-) Hydro____ ic acid (hydrochloric acid, HCl) add H+ ions _________ic acid (chloric acid, HClO3) (perchloric acid, HClO4) _________ ate (chlorate, ClO3-) (perchlorate, ClO4-) add H+ ions _________ite (chlorite, ClO2-) (hypochlorite, ClO-) ______ous acid (chlorous acid, HClO2) (hypochlorous acid, HClO) add H+ ions
Increasing acid Strength Increasing base Strength Increasing acid Strength Increasing base Strength Brown, LeMay, Bursten, Chemistry 2000, page 625
[A-] [H3O+] 1 x 10-14 Ka = [HA] = [OH-] 1 x 10-14 = [H3O+] Equilibrium and pH Calculations Weak acid Strong acid HA + H2O H3O+ + A- HA + H2O H3O+ + A- acid-dissociation constant calculations [HA] = [H3O+] [H3O+] + antilog(-pH) [OH-] -log [H3O+] = pH - 0 7 14 Tocci, Viehland, Holt Chemistry Visualizing Matter 1996, page 525