acids and bases. additional key terms hydroxidehydronium outline the historical development of acid...
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ACIDS AND BASES
Additional KEY TermsHydroxide Hydronium
• 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)
HCl (aq) → H+ (aq) + Cl–
(aq)
NaOH (aq) → Na+ (aq) + OH–
(aq)
2. The Bronsted-Lowry Theory
Lowry
Bronsted
20 years later:
What about ammonia (NH3) 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:
NH3 (g) + H2O(l) NH4+
(aq) + OH-(aq)
H+
acceptor
Base is a proton (H+) acceptor:
donor
Follow the Hydrogen ion – who donated it, who accepted it.
H3O+ ion called the hydronium ion
H+
acceptordonor
Acids is a proton (H+) donor:
Hydrochloric acid donates a proton to water:
HCl(g) + H2O(l)
H+ H2O
H3O+(aq)
H3O+ splits apart quickly, so H3O+ 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.
HCO3- + OH- CO3
2- + H2OH+
acceptordonor
HCO3-
+ H2O H2CO3 + OH-
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(H2O)63+ + H2O H3O
+ + Fe(H2O)5(OH)2+ H+
H
All electrons are attracted inwards, so Hydrogen ion has
nothing to lose and leaves
Acids Base • electron acceptor ● electron donor
3. Gilbert Lewis Definition
CH3COO-(aq) + H2O(l) OH-
(aq) + CH3COOH (aq)
H+
base acidWhat 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.
NH3 (g) + H2O(l)
base acid
NH4+
(aq) + OH-(aq)
Con. baseCon. acid
You are looking at the forward and reverse reactions – which compound donates for which direction?
B + H2Obase acid
BH+ + OH-
Con. baseCon. acid
Each is called a conjugate pair.
HA + H2Obaseacid
H3O+ + A-
Con. baseCon. acid
These are generic equations for an acid or base reaction
Additional KEY TermsHydroxide Hydronium
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