1. Chapters 9 & 19 Chemistry 1K Cypress Creek High School
Unit 13: Acids & Bases
Chapters 9 & 19
Chemistry 1K
Cypress Creek High School

2. Properties of Acids Taste sour Feel watery
Are electrolytes: conduct an electrical current by forming H+ ions in solution
React with metals
Corrosive
pH < 7 2

3. Arrhenius’ Definition of Acids
Arrhenius defined acids as anything that produces H+ ions in solution
Monoprotic acids – have 1 ionizable hydrogen (HCl)
Diprotic acids – have 2 ionizable hydrogens (H2SO4)
Triprotic acids – you guessed it…they have 3 (H3PO4)
Produces H+ ions in solution 3

4. Bronsted-Lowry Definition of Acids
According to Bronsted-Lowry an acid is a chemical that is able to lose or "donate" a hydrogen ion (aka proton because the H+ contains no electrons or neutrons) during a reaction.
Acid loses a hydrogen ion

5. Naming an Acid hydro ______ic acid ate ions: _________ic acid
Binary acids (H + nonmetal):
hydro ______ic acid
Ternary acids (H + polyatomic ion):
ate ions: _________ic acid
ite ions: _________ous acid
Name the following acids:
HBr
H2SO3
H3PO4
Write the formulas for the following acids:
Hydrosulfuric acid
Nitrous acid
Chromic acid 5

6. Properties of Bases Taste bitter Feel slippery Corrosive
Are electrolytes: conduct an electrical current by forming OH- ions in solution
pH > 7 6

7. Arrhenius’ Definition of Bases
Arrhenius defined Bases as anything that produces OH- ions in solution
Produces OH- ions in solution 7

8. Bronsted-Lowry Definition of Bases
A chemical species that is able to gain or "accept" a hydrogen ion (aka proton because the H+ contains no electrons or neutrons) during a chemical reaction.
Base gains a hydrogen ion

9. Naming a Base Formula is either: Metal + OH- or Ammonium + OH-
Name + hydroxide
Name the following bases:
NaOH
NH4OH
NH3
Ca(OH)2
Write the formulas for the following bases:
Magnesium hydroxide
Aluminum hydroxide 9

10. Conjugates Conjugate acid is formed when a base accepts a proton (H+)
Conjugate base is formed when a acid donates a proton (H+) 10 10

11. Conjugate Acid/Base Pairs
Acids and Bases are always reactants
Conjugate acids and conjugate bases are always products.
Conjugate acid is the product that remains when a base has accepted a proton.
Conjugate base is the product that remains when an acid has donated a proton.
Ex NH3 + H2O → NH4+ + OH-
(base) (acid) (c.acid) (c.base)

12. Conjugate Practice NH3(g) + H3O+(aq)  NH4+(aq) + H2O(l)
CH3OH(l) + NH2-(aq)  CH3O-(aq) + NH3(g)
OH-(aq) + H3O+(aq)  H2O(l) + H2O(l)
NH2-(aq) + H2O(l)  NH3(g) + OH-(aq)
Base
Acid
C.Acid
C.Base
Acid
Base
C.Base
C.Acid
Base
Acid
C.Acid
C.Base
Base
Acid
C.Acid
C.Base

13. Amphoteric
Some substances can act as an acid or a base and are called amphoteric.
Ex. H2O can act as both an acid and a base
NH3 + H2O → NH4+ + OH-
(base) (acid)
H+ was lost by water
HCl + H2O → H3O+ + Cl-
(acid) (base)
H+ was gained by water 13

14. Indicators
Indicators are organic substances that change colors in an acid or a base (sometimes paper, sometimes liquids)
Acids turn…
Litmus paper – red
Phenolphthalein – clear
Universal indicator – yellow/orange/red
Bases turn…
Litmus paper – blue
Phenolphthalein – magenta (hot pink)
Universal indicator – dark green/blue/purple 14

15. The pH Scale
pH is a mathematical scale in which the concentration of hydrogen ions (H+) in a solution is expressed as a number from 0 to 14.
The pH scale is a convenient way to describe the concentration of H+ ions in acidic solutions, as well as the hydroxide ions in basic solutions.

16. pH and pOH Scale
[H+] and [OH-] are inverses: the exponents always add up to -14
Ex: If [H+] = 1.0x10-3 M, then [OH-] = 1.0x10-11 M

17. Household Items & the pH Scale

18. Mathematical Definition of pH and pOH
The letter “p” in front of pH and pOH refers to the negative log.
A logarithm (log) is the power to which a base, such as 10, must be raised to produce a given number.
For example: the logarithm of 1000 to base: 10 is 3, because 3 is the power to which ten must be raised to produce 1000: 103 = 1000

19. pH and pOH
The pH of a solution equals the negative logarithm of the hydrogen ion concentration.
Chemists have also defined a pOH scale to express the basicity of a solution.
In an acidic solution, [H+] > [OH-]
In a basic solution, [H+] < [OH-]
pH + pOH = 14 pH
pOH
Stands for “power of hydrogen”
Stands for “power of hydroxide”
Shows the [H+] in a solution
Shows the [OH-] in a solution
pH = -log[H+]
pOH = -log[OH-]

20. pH and pOH Calculations
Notice the relationship between concentration and the pH/pOH value:
Toothpaste has a hydrogen ion concentration of 10–10M, so its pH is 10.
pH = -log[10-10] = 10
Pure water, which is neutral, has a pH of 7. That means its hydrogen ion concentration is 10–7M.
7 = -log[H+] ; [H+] = 10-7

21. Relating pH, pOH, [H+], & [OH-]4 2
1x10-6
1.26x10-4
9.64
13.7
1.82x10-4 10
1x10-4
1x10-10 12
1x10-12
1x10-2 6 8
1x10-8
10.1
3.9
7.9x10-11
4.36
4.37x10-5
2.29x10-10
0.3
2.00x10-14
5.01x10-1
3.74
10.26
5.50x10-11