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ACIDS AND BASES. Additional KEY Terms HydroxideHydronium Outline the historical development of acid base theories. Include: Arrhenius, Bronsted-Lowry,

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Presentation on theme: "ACIDS AND BASES. Additional KEY Terms HydroxideHydronium Outline the historical development of acid base theories. Include: Arrhenius, Bronsted-Lowry,"— Presentation transcript:

1 ACIDS AND BASES

2 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

3  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.

4 1. Arrhenius Definition Svante Arrhenius ( ) 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)

5 HCl (aq) → H + (aq) + Cl – (aq) NaOH (aq) → Na + (aq) + OH – (aq)

6 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

7 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.

8 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)

9 Amphoteric: a substance which can act as either an acid or a base. Water is amphoteric. Bicarbonate ion is also amphoteric. HCO OH - CO H 2 O H+H+ acceptordonor HCO H 2 OH 2 CO 3 + OH - H+H+ acceptor donor

10 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

11 Step 2: Loss of H + making acidic solution. Fe(H 2 O) 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

12 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 +

13 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?

14 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

15 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


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