1. ACIDS AND BASES NOTES
Chemistry Chapter 18

2. Everyday Acids acid in rain carves away limestone to form caves
ants use formic acid to alert each other to danger
citrus acid gives orange juice its flavor

3. Everyday Bases sodium hydroxide found in soap for cleaning hands
calcium hydroxide found in Drano for unclogging pipes
aluminum hydroxide found in TUMS for relieving acid indigestion

4. What makes a solution acid or base?
Water - most common solvent, breaks down into ions:
H2O  H+ + OH-
The relative amounts of ions determine if a solution is acidic, basic, or neutral:
Acidic = more H+ ions
Basic = more OH- ions
Neutral = equal amounts of both ions

5. Characteristics of Acids and Bases
tastes sour
reacts with metals/corrosive
feels like water
turns litmus red
becomes less acidic when reacts with bases
pH < 7.0
tastes bitter
do not react with metals
feels slippery
turns litmus blue
becomes less basic when reacts with acids
pH > 7.0

6. Arrhenius Acids & Bases
Arrhenius Acid = releases hydrogen ions, H+
ex. HCl + H2O  H+ + Cl-
Arrhenius Base = releases hydroxide ions, OH-
ex. NaOH + H2O  Na+ + OH-
Definitions did not explain why some substances can act like bases even though they do not contain hydroxide ions, OH-

7. Bronsted-Lowry Acids & Bases
H2O has gained a H+
Bronsted-Lowry Acids & Bases
HCl has lost a H+
Bronsted-Lowry Acid = any substance that can donate a hydrogen ion (proton)
Bronsted-Lowry Base = any substance that can accept a hydrogen ion (proton)
opposite of an acid

8. Conjugate Acids & Bases
Conjugate acid = formed from the base by the addition of a proton (H+)
base  conjugate acid
Ex. NH3 + H2O  NH OH-
Conjugate base = formed from the acid by loss of a proton (H+)
acid  conjugate base

9. Conjugate Acid-Base Pairs
consists of two substances related to each other by the donating and accepting of a single proton

10. Water – Acid or Base?? water can act like an acid or a base
Amphoteric: substances can act as both an acid or base (gives or accepts protons)
Examples
water as an acid: NH3 + H2O  NH4+ + OH-
water as a base: H2O + HCl  H3O+ + Cl-

11. Acid Categories Monoprotic acids – have only one proton to donate
examples: HNO3, HF, HBr
Polyprotic acids – have two or more protons to donate
examples: H2SO4, H2CO3, H3PO4

12. Strength of Acids & Bases
Strong acids/bases: ionize completely in solution, will conduct electricity- show bright light
examples: HCl, HBr, KOH, NaOH, LiOH
Weak acids/bases: do not break down completely in solution, produce very little electricity – show dim light
examples: H2O, HCN, Ca(OH)2

13. Strength of Conjugates
Weak acids: strong conjugate bases
Weak bases: strong conjugate acids
Strong acids: weak conjugate bases
Strong bases: weak conjugate acids