Acids and Bases

Acids Taste sour Turn litmus paper red React vigorously with metals Conduct electricity Corrosive Make H3O+ Proton donors (BrØnsted-Lowry)

Bases Turn litmus blue Taste bitter Feel slippery Conduct electricity Corrosive Make OH- ions Proton acceptor (BrØnsted-Lowry)

Dissociation Ionic compound breaks apart into its ions Write the dissociation equation for the following: NaOH Ca(OH)2 HCl H2CO3

Strong vs. Weak (electrolytes/acids/bases) Strong completely dissociate Weak partially dissociate A strong (acid/base) completely ionizes in a solvent. A weak (acid/base) partially ionizes in a solvent. In equilibrium Few H+/OH- are released in aqueous solution.

Arrhenius Acids Any substance that, when added to water, increases the hydronium (H3O+) concentration. Number of ionizable H determines how many H3O+ are made. Ionizable H are at the beginning of the cmpd HCl H2SO4

Arrhenius Base Any substance that, when added to water, increases the hydroxide (OH-) Number of OH- in formula is how many OH- are made NaOH Ca(OH)2

Problems w/Arrhenius Limited to aqueous solutions Cannot classify substances that can act as either acids or bases.

Brønsted-Lowry Classification Brønsted-Lowry acid - donates a proton look at the reaction: (1) HCl  H+ + Cl− (2) H+ + H2O  H3O+ HCl is an Arrhenius acid- makes a H3O+. HCl is a Brønsted-Lowry acid because it donates a proton (H+).

Brønsted and Lowry Base A proton acceptor. Ammonia (NH3)-proton acceptor NH3- makes OH- in water so Arrhenius base

Classification Arrhenius acids/bases are also Brønsted-Lowry acids/bases Brønsted-Lowry acids/bases are not always Arrhenius acids/bases

Conjugate Acids and Bases When an acid looses a proton, it becomes a conjugate base When a base gains a proton, it becomes a conjugate acid Write the conjugate base for the following: HF H2CO3 Write the conjugate acid for the following: NO3- HCO3-

Every acid has a conjugate base Every base has a conjugate acid We can look at an acid/base equations and determine acid/base pairs.

When the reaction is reversed, we can identify another acid and another base. But it is the same acid/base pairs as before

HCl + H2O → H3O+ + Cl-

Amphoteric Substances that can be either both an acid or a base can both donate and accept protons. Example: Water Has properties of both acid and base Can donate or accept H+ Hydrogen carbonate HCO3- + H2O → H2CO3 + OH- (base; H+ acceptor) HCO3- + H2O → CO3-2 + H3O+ (acid; H+ donor)