Aim: What are acids and bases?

Acids 1.Acids can be strong or weak electrolytes in aqueous solutions. 2.Acids (ex: HCl) react with certain metals to produce H 2 (g). 3.Acids cause color changes in acid-base indicators: Blue litmus paper turns red in an acid Phenolphthalein is colorless in an acid 4.Acids have a sour taste Table K has a list of Common Acids

Bases 1.Bases can be strong or weak electrolytes in aqueous solutions 2.Bases cause color changes in acid-base indicators: Red litmus paper turns blue in a base Phenolphthalein is pink in a base 3.Bases feel slippery and taste bitter. Table L has a list of Common Bases

Arrhenius Acid An Arrhenius acid gives off H + (hydrogen ions) in aqueous solutions. Ex: HCl, HBr, H 2 SO 4 The H + attach to H 2 O to form H 3 O + (hydronium ion). HCl + H 2 O  H + + Cl - + H 2 O  Cl - + H 3 O +

Arrhenius Base An Arrhenius base has OH and give off OH - (hydroxide ions) in an aqueous solution. Ex: NaOH, KOH, Ca(OH) 2 NaOH  Na + + OH - Group 1 metals react with water to produce bases. 2Na(s) + 2H 2 O(l)  2 NaOH(aq) +H 2 (g)

Question Which substance can be classified as an Arrhenius acid? 1.HCl 2.NaCl 3.LiOH 4.KOH

Question Which substance can be classified as an Arrhenius base? 1.HCl 2.NaOH 3.LiNO 3 4.KHCO 3

Question According to the Arrheneius theory, a substance that is classified as an acid will always yield 1.H + (aq) 2.NH + 4 (aq) 3.OH - (aq) 4.CO 3 2- (aq)

Bronsted-Lowry Acids and Bases An acid is an H + donor(proton donor). A base is an H + acceptor (proton acceptor) HCl(g) + H 2 O(l)  H 3 O + (aq) + Cl-(aq) HCl is an acid because it donates an H + to the H 2 O. Donates H + ACID BASE Accepts H +

Bronsted-Lowry Acids and Bases NH 3 (aq) + H 2 O(l)  NH 4 + (aq) + OH - (aq) NH 3 is a base because it accepts an H + from the H 2 O. Accepts H + Donates H + ACID BASE

Bronsted-Lowry Acids and Bases Water can either be a proton donor (acid) or a proton acceptor (base); water is amphoteric.

Question According to the Bronsted-Lowry theory, a chloride ion (Cl - ), acts as a base when it combines with 1.An OH - ion 2.A K + ion 3.An H - ion 4.An H + ion

Question According to the Bronsted-Lowry theory, an acid is 1.A proton donor, only 2.A proton acceptor, only 3.A proton donor and a proton acceptor 4.Neither a proton donor nor a proton acceptor

Conjugate acids and bases NH 3 (aq) + H 2 O(l)  NH 4 + (aq) + OH - (aq) BASEACIDCONJUGATECONJUGATE ACIDBASE A conjugate base is what is remained after the acid gives up H +. A conjugate acid is what is formed when a base accepts a proton.

Question In the reaction H 2 PO H 2 O  H 3 PO 4 + OH - which pair represents an acid and its conjugate base? 1.H 2 O and H 2 PO H 2 O and H 3 PO 4 3.H 3 PO 4 and OH - 4.H 3 PO 4 and H 2 PO 4 -

Question Given the reaction at equilibrium HSO H 2 O  H 3 O + + SO 4 2- According to the Bronsted-Lowry theory, the two bases are 1.H 2 O and H 3 O + 2.H 2 O and SO H 3 O + and H 2 SO H 3 O + and SO 4 2-