Acids and Bases Kelley Kuhn CCA

Typically acidic substances pH lower than 7 Fruit Carbonated beverages (not all of them, thank goodness!) Salad dressings Personal hygiene Shampoo Mouthwash Body lotions Body sprays Lip treatment Antibacterial

Typically basic substances pH higher than 7 Milk Blood Cleaning products Soaps Bleach

Arrhenius: donates hydrogen ion in solution Acids Bases Arrhenius: donates hydrogen ion in solution Arrhenius: donates hydroxide ion (OH-) in solution Bronsted/Lowry: proton (hydrogen ion) donor HA + H2O  H3O+ + A- Acid base conj. acid conj. base Bronsted/Lowry: proton acceptor NH3 + H2O  NH4+ + OH- Base acid conj. acid conj. base Strong acids completely dissociate, can have very low pHs and form strong electrolytic solutions. Strong bases completely dissociate, can have very high pHs and form strong electrolytic solutions.

Strong acids you must know: Strong bases you must know: Weak acids only partially dissociate, have pHs closer to neutral, and are weak electrolytes. Weak bases only partially dissociate, have pHs closer to neutral, and are weak electrolytes. Strong acids you must know: Hydrochloric acid: HCl Nitric acid: HNO3 Sulfuric acid: H2SO4 Strong bases you must know: Sodium hydroxide: NaOH Potassium hydroxide: KOH Calcium hydroxide: Ca(OH)2 Common weak acids: Phosphoric acid: H3PO4 Acetic acid: HC2H3O2 Common weak bases: Ammonia: NH3 Any ionic compound that ends in “OH”

Attributes of acids Acids are sour, have a pH below seven. The ion that is dominant in all acids is H+, which joins with the water molecule to generate H3O+, which is called hydronium ion (or occasionally oxonium ion)

Attributes of bases Bases are bitter, slippery, and have a pH above seven. The ion that is dominant in all basic solutions is OH-, or the hydroxide ion. If you place a pure alkali or alkaline earth metal in water, you will generate hydrogen gas and OH- ion. Example: K(s) + 2 H2O(l)  K+(aq) + 2 OH-(aq) + 2 H2(g)

Conjugate acids and bases Bronsted and Lowry proposed the idea that acids and bases exist as conjugate pairs, with the base always having one less H+ (or proton) than its conjugate acid. Examples: NH3 and NH4+ Which is the conjugate base and which is the conjugate acid? What is the conjugate acid for HCO31-? What is the conjugate base for HCO31-?

And your formulas are: pH = -log[H+] pOH = -log [OH-] [H+] = antilog(-pH) [OH-] = antilog(-pOH) pOH + pH = 14 The relationship between [H+] and [OH-] is inversely proportional and their product is always 1 x 10-14 for any water-based solution! [H+] x [OH-] = 1 x 10-14

In water, [H+] and [OH-] are both 1 x 10-7 M In water, [H+] and [OH-] are both 1 x 10-7 M. Based on these concentrations, what is the pH of water? What is the pOH? Do the math to prove this. Why do we call this solution neutral? If a solution has a [H+] of 1.2 x 10-2 M, what is its pH? What is the concentration of [OH-]?