1. Chapter 14
Acids, Bases, and pH

2. Comparing of Acids and Bases
Observable properties –
Acids are sour
Bases are bitter and slippery to touch
***note – taste and touch
are not safe ways to test
chemicals

3. Comparing of Acids and Bases
Acids and bases turn certain dyes different colors
acids turn litmus dye red
bases turn litmus dye blue

4. Many common substances are acids or bases common acids –
citric acid, vinegar,
hydrochloric acid,
sulfuric acid
common bases –
lye/soap, ammonia,
sodium hydroxide,
other metal hydroxides

5. Reactions Acids react with metals that are MORE active than hydrogen
bases do NOT usually react with metals

6. Reactions
acids also react with ionic compounds that contain the carbonate ion, CO3-2
reaction produces carbon dioxide gas, water, and another compound

7. Submicroscopic Behavior of Acids
definition of acid – a substance that produces hydronium ions, H3O+ , when it dissolves in H2O
Ex.
hydronium ions are formed from the transfer of a H+ ion from the acid to H2O

8. Submicroscopic Behavior of Acids
acidic hydrogen – any hydrogen atom that can be transferred to H2O.
to distinguish acidic H’s from other H’s in the compound, acidic H’s are written 1st.
HCl HC2H3O2
HNO3 H2SO4

9. monoprotic acids contain only one acidic hydrogen

10. polyprotic acids with two acidic hydrogens are diprotic acids.
polyprotic acids with three acidic hydrogens are triprotic acids

11. Chemical Reaction Shorthand
general format for acid dissociation
HA + H2O (l) H3O+ (aq) + A- (aq)
HA (aq) H+ (aq) + A- (aq)
Reaction of acid and H2O to form ions is called acid ionization

12. Submicroscopic Behavior of Bases
definition of base – a substance that produces hydroxide ions, OH- when dissolved in water
2 kinds
ionic bases
covalent bases

13. Simple Bases (ionic)
metal hydroxide = metal ion + OH ion
the metal hydroxide dissociates in H2O to form a metal ion and a hydroxide ion
***note - H2O does not react here, there is no actual transfer of ions as in the next example and with acids

14. covalent bases react with H2O to form OH- ions
Bases that Accept H+
covalent bases react with H2O to form
OH- ions
there is a transfer of H+ from the water to the base
General equation for bases that accept H+:
B + H2O (l) BH+ (aq) + OH- (aq)
NH3 (g) + H2O (l) NH4+ (aq) + OH- (aq)
ammonia + water ammonium hydroxide solution

15. Other Acids and Bases certain compounds act like acids and bases-
these compounds are: oxides -compounds with oxygen bonded to 1 other element
they are called anhydrides - contain no water

16. Other Acids and Bases
acidic anhydrides—nonmetal oxides which react with water to form acids
CO2 + H2O H2CO3
SO3 + H2O H2SO

17. Other Acids and Bases
basic anhydrides—metal oxides which react with water to form acids
Na2O + H2O NaOH
ZnO + H2O Zn(OH)2

18. Acid Base ion produced when dissolved in H2O hydronium ions = H3O+
produce hydroxide ions (OH-) when dissolved in water
properties
tart, sour,
bitter, slippery,
examples
citric acid, vinegar, hydrochloric acid,
lye/soap, ammonia, metal hydroxides
formula
usually have H in front of the formula or at the end: HCl, CH3COOH
usually have OH at the end of the formula: KOH, ammonia (NH3) is also a base,
litmus
red
blue pH
less than 7
greater than 7

19. Strengths of Acids and Bases
strong acids completely dissociate into ions
no molecules left intact
weak acids partially dissociate (not all come apart) into ions

20. Strengths of Acids and Bases
strong bases completely dissociate (come apart) into ions
weak bases partially dissociate (not all come apart) into ions

21. strength vs. concentration
weak and strong refer to dissociation only
concentrated & dilute = molarity—(M); amount of particles in the solution

22. The pH Scale pH = mathmatical scale; range is 100 to 10-14
= concentration of H3O+ ions
= number from 0 to 14.
acid pH < 7 neutral pH = 7 base pH > 7

24. pOH = concentration of OH- ions
pH + pOH = 14
Water is mostly neutral [H+] = [OH-]
Acidic solutions: [H+] > [OH-]
Basic (alkaline) solutions: [OH-] > [H+]

25. pH of common substances

26. Example:
If [H+] of a solution = 1.0 x M
Find pH.
Find pOH.
Find [OH-].
Acid, base, or neutral?
a) [H+] = 1.0 x M
b) pH + pOH = 14; pOH = 14
c) [H+] [OH-] = 10-14M [10-11] [OH-] = M
d) pH > 7
pH = 11
pOH = 3
[OH-] = 10-3 M
base

27. Example:
If [OH-] of a solution = 1.0 x 10-9 M
Find pOH.
Find pH.
Find [H+].
Acid, base, or neutral?
a) [OH-] = 1.0 x 10-9 M
b) pH + pOH = 14; pH + 9 = 14
c) [H+] [OH-] = 10-14M [H+] [10-9] = M
d) pH < 7
pOH = 9
pH = 5
[H+] = 10-5 M
acid