Presentation on theme: "ACIDS AND BASES. Additional KEY Terms HydroxideHydronium Outline the historical development of acid base theories. Include: Arrhenius, Bronsted-Lowry,"— Presentation transcript:
Additional KEY Terms HydroxideHydronium Outline the historical development of acid base theories. Include: Arrhenius, Bronsted-Lowry, Lewis Write balanced acid/base chemical equations. Include: conjugate pairs, amphoteric
Taste sour Burn when touching skin Turn blue litmus red Neutralize basic solutions Corrosive to metals Strong or weak electrolytes ACIDS BASES Taste bitter Feel slippery Turn red litmus blue Neutralize acidic solutions Strong or weak electrolytes You should already be aware of most of these properties…except the taste. Don’t eat stuff in the lab, please.
1. Arrhenius Definition Svante Arrhenius (1859 - 1927) Acids Yield hydrogen ions (H + ) in aqueous solution Bases Yield hydroxide ions (OH - ) in aqueous solution H + is also called a “proton” because a Hydrogen atom without its electron is just a proton (it has no neutrons)
2. The Bronsted-Lowry Theory Lowry Bronsted 20 years later: What about ammonia (NH 3 ) Bronsted? It acts as a base, but doesn’t have OH -. I guess we need I new definition for acid and base, Lowry! Acids proton (H + ) donor Base proton (H + ) acceptor
Ammonia accepts a proton from water: NH 3 (g) + H 2 O (l) NH 4 + (aq) + OH - (aq) H+H+ acceptor Base is a proton (H + ) acceptor: donor Follow the Hydrogen ion – who donated it, who accepted it.
H 3 O + ion called the hydronium ion H+H+ acceptordonor Acids is a proton (H + ) donor: Hydrochloric acid donates a proton to water: HCl (g) + H 2 O (l) H+H+ H2OH2O H 3 O + (aq) H 3 O + splits apart quickly, so H 3 O + and H + are written interchangeably. + Cl - (aq)
Amphoteric: a substance which can act as either an acid or a base. Water is amphoteric. Bicarbonate ion is also amphoteric. HCO 3 - + OH - CO 3 2- + H 2 O H+H+ acceptordonor HCO 3 - + H 2 OH 2 CO 3 + OH - H+H+ acceptor donor
Transition metal ions with charges of 2+ or 3+, create an acidic solution with water. Step 1: Formation of a hydrate. Water’s electrons are attracted to the BIG positive charge on Fe
Step 2: Loss of H + making acidic solution. Fe(H 2 O) 6 3+ + H 2 O H 3 O + + Fe(H 2 O) 5 (OH) 2+ H+H+ H All electrons are attracted inwards, so Hydrogen ion has nothing to lose and leaves
AcidsBase electron acceptor ● electron donor 3. Gilbert Lewis Definition CH 3 COO - (aq) + H 2 O (l) OH - (aq) + CH 3 COOH (aq) H+H+ base acid What about those metals? I think we need a broader definition? Negative ions have extra electrons to donate to the lonely H +
Conjugate acid is what remains after a base has accepted a proton. Conjugate base is what remains after the acid has donated its proton. NH 3 (g) + H 2 O (l) base acid NH 4 + (aq) + OH - (aq) Con. base Con. acid You are looking at the forward and reverse reactions – which compound donates for which direction?
B + H 2 O base acid BH + + OH - Con. base Con. acid Each is called a conjugate pair. HA + H 2 O base acid H 3 O + + A - Con. baseCon. acid These are generic equations for an acid or base reaction
Additional KEY Terms HydroxideHydronium CAN YOU / HAVE YOU? Outline the historical development of acid base theories. Include: Arrhenius, Bronsted-Lowry, Lewis Write balanced acid/base chemical equations. Include: conjugate pairs, amphoteric