1. Acids

2. Definition of Acid HCl + H2O  H3O+ + Cl–
Acids are substances that contain H+ ions that ionize when dissolved in water.
Arrhenius acid: a compound that increases the concentration of H+ ions that are present when added to water. These H+ ions form the hydronium ion (H3O+) when they combine with water molecules
HCl + H2O  H3O+ + Cl–

3. – + Bronsted-Lowry acid: acid is a proton (H +) (hydrogen ion) donor.
HA(aq)⇌A-(aq) + H +(aq) H Cl O – +

4. ABOVE CAN REPLACE BELOW
Properties of Acids
ABOVE CAN REPLACE BELOW
Acids eat away (oxidize) active metals
Metals like Li, Mg and Zn can be oxidized by an acid to produce hydrogen gas.
The three metals listed below hydrogen (Cu, Ag and Au) cannot be oxidized by an acid.
This is a single replacement reaction:
2 Li + 2 HCl  2 LiCl + H2
Ca + 2HCl  CaCl2 + H2
The active metal kicks out the hydrogen in the acid.

5. b) Acids have a pH less than 7.
pH is a scale that measures the acidity or alkalinity of a solution.
A pH of 7 is a neutral solution, and acids have a pH of less than 7
Each decrease of one in pH is a tenfold increase in acid strength.
An acid with a pH of 3 is ten times more acidic than one with a pH of 4, and one hundred times more acidic than a solution with a pH of 5.

6. pH acid rain (NOx, SOx) pH of 4.2 - 4.4 in Washington DC area
0-14 scale for the chemists 2 3 4 5 6 7 8 9 10 11 12
acidic
(H+) > (OH-)
25oC
(H+) = (OH-)
distilled water
basic or alkaline
(H+) < (OH-)
normal rain (CO2)
pH = 5.3 – 5.7
fish populations
drop off pH < 6 and to zero pH < 5
natural waters pH =

7. Strong acids: c) Acidic solutions conduct electricity.
Acids are electrolytes, because they form ions in solution.
Strong acids ionizes completely in water, conducts electricity well HCl  H+ + Cl-
Weak acids release few hydrogen ions in water
HOCl + H2O ↔ H3O+ + ClO-
Strong acids:
HCl H2SO4 HNO3
HBr HI HClO4
hydrochloric
sulfuric
nitric
chloric
HClO3
hydrobromic
hydroiodic
Perchloric

8. Complete dissociation of Acids
CHM 101
Sinex
Complete dissociation of Acids HA
What happens to the HA molecules in solution?

9. Strong Acid Would the solution be conductive?
100% dissociation of Acid HA
Strong Acid H+ A-
Would the solution be conductive?

10. Partial dissociation of HA
Weak Acid A-
Would the solution be conductive?

11. At any one time, only a fraction of the molecules are dissociated.
HA  H A- HA H+
Weak Acid A-
At any one time, only a fraction of the molecules are dissociated.

12. d) Dilute solutions of acids taste sour.
e) Acids react with carbonates to form CO2, salt and water vapor
Baking soda and vinegar:
NaHCO3 (s) + HC2H3O2 (aq)  CO2 (g) + H2O (l) + NaC2H3O2 (aq)
This is the “volcano” reaction, the CO2 gas given off causes the solution to foam up and out.

13. f) Acids can be formed by reaction of gaseous oxides with water
Burning fossil fuels releases nonmetallic oxides (CO2, NO2, SO2 and similar molecules) into the atmosphere.
When they combine with the water in the atmosphere, they form weak acids that can cause ecological problems.
Plants and fish thrive in a narrow range of pH values.

14. What is acid rain? Dissolved carbon dioxide lowers the pH
CO2 (g) + H2O  H2CO3  H+ + HCO3-
Atmospheric pollutants from combustion
NO, NO H2O …  HNO3
both
strong
acids
SO2, SO H2O …  H2SO4
pH < 5.3

17. HCl Naming Acids Hydrochloric acid
Binary Acids: hydro- prefix, followed by nonmetal ion name with last syllable replaced with –ic acid
HCl
hydro
+chloride – ide
+ ic acid
Hydrochloric acid

18. HNO3 HNO2 Naming Acids Nitric acid Nitrous acid + ic acid + ous acid
Ternary Acids: no hydro- prefix,
polyatomic ion name followed by –ic acid, if ion ends in -ide, –ate
Polyatomic ion name followed by –ous acid if ion ends in –ite
HNO3
HNO2
nitrate
+ ic acid
nitrite
+ ous acid
Nitric acid
Nitrous acid

19. Bases

20. Bases
Bases are substances that contain hydroxide (OH-1) ions dissolved in aqueous solution.
Arrehnius Base: a compound that increases the concentration of (OH-) hydroxide ions when added to water
NH3 + H2O  NH4+ + OH-

21. Bronsted-Lowry Bases: base is a substance that can accept a proton (H+)
NaOH(aq)→Na+ (aq)+OH- (aq) H N O – +

22. Properties of Bases a) Bases have a pH greater than 7
pH is a scale that measures the acidity or alkalinity (basicity) of a solution.
A pH of 7 is a neutral solution, and bases have a pH of more than 7.
Each increase of one in pH is a tenfold increase in base strength.
A base with a pH of 10 is ten times more basic than one with a pH of 9, and one hundred times more basic than a solution with a pH of 8.

23. If it is not a strong base then it is a weak base!!
b) Basic solutions conduct electricity.
Bases are electrolytes, because they form ions in solution.
Strong bases ionizes completely in water
NaOH  Na+ + OH-
Weak bases releases few hydroxide in water
NH3 + H2O ↔ NH4+ + OH-
Strong Bases:
LiOH NaOH KOH
Ca(OH)2 Ba(OH)2 Sr(OH)2
If it is not a strong base then it is a weak base!!
RbOH
Rubidium hydroxide
CsOH
Cesium hydroxide
Lithium hydroxide
Sodium hydroxide
Potassium hydroxide
Calcium hydroxide
Barium hydroxide
Strontium hydroxide

24. c) Bases taste bitter
d) Bases can be formed when Group 1 and 2 metals react with water, hydrogen is released too.
2 Na (s) + H2O (l) ↔ 2 NaOH (aq) + H2 (g)
Mg (s) + 2 H2O (l) ↔ Mg(OH)2 (aq) + H2 (g)
e) Bases hydrolyze fats (turns them into soap, also called “saponification”)
Ammonium hydroxide (NH3 (aq) or NH4OH) is a solution used to clean floors and countertops of greasy buildup or residue.

25. LiOH lithium hydroxide Ca(OH)2 calcium hydroxide
Naming bases
Name the metal CATION first; it keeps its name as listed in the Periodic Table.
The polyatomic ion "hydroxide" (OH-) also keeps its name.
Examples:
LiOH lithium hydroxide
Ca(OH)2 calcium hydroxide
NH4OH ammonium hydroxide

26. Conjugates & Amphoteric substances

27. Acid- conjugate base base- conjugate acid
Acid, Base Conjugates
Acids are proton (H+) donors.
Bases are proton (H+) acceptors.
Conjugate acid – base pair: The pair of acid and base that differ by a H+.
Acid- conjugate base base- conjugate acid
HCl + H2O  Cl– + H3O+
acid
conjugate base
base
conjugate acid

28. H+ Amphoteric Substance H2O H3O+ OH– SO42– ↔ ↔ H2SO4 HSO4– CO32– ↔ ↔
Amphoteric substance: Substance that can either donate or accept a hydrogen ion.
Conjugate Base
Conjugate Acid
– H+
+ H+ H+
OH–
hydroxide
H2O
H3O+
hydronium ↔ ↔
SO42– ↔
– H+
+ H+ ↔
H2SO4
HSO4– -2 -1 +1 +2
CO32– ↔
– H+
+ H+ ↔
H2CO3
HCO3–

29. Determination of Acids and Bases

30. How to determine acids and bases
pH probes
pH probes contain an electrode that detects electrical conductivity.
Before using this electronic device, it has to be calibrated by giving it a taste of two different solutions with different pH’s.
These come in pocket devices that run on batteries or in computer interface probe form.

31. 2. Acid-Base Indicators and narrowing down pH using multiple indicators
Methyl orange is RED from a pH of 3.2 or lower, and YELLOW from a pH of 4.4 or more.
The middle of the range is an intermediate color (in this case, ORANGE).

32. Hydronium ion [H3O+] and hydroxide ion [OH-]

33. Acidity and Bascitiy
The concentration of hydronium ions in a solution expresses its acidity.
The concentration of hydroxide ions in a solution expresses its basicity.
H3O+
OH–
When the concentration of H3O+ goes up, the concentration of OH− goes down, and vice versa.