1. Chapter 10 Acids (酸) and Bases （碱）

2. 10.1 Acids donate protons, bases accept them
Sulfuric acid is the number one manufactured chemical, 85 billion pounds (40,000,000 tons) annually in US. Acid has “sour” taste.
Bases have “bitter” taste and slippery feel. In US, 25 billion pounds (10,000,000 tons) of NaOH was manufactured.
Examples of acides

3. By definition, acids are chemicals that donate hydrogen ions, and bases are chemicals that accept them.
HCl H2O Cl- +H3O+ (hydronium ion)
H+ donor H+ acceptor
(acid) (base)
H2O + NH3 OH- + NH4+
H+ donor H+ acceptor H+ acceptorH+ donor
(acid) (base) (base) (acid)

4. A salt is the product of an acid-base reaction (neutralization 中和)
Acid Base Salt Water
HCN NaOH NaCN H2O
Hydrogen Sodium Sodium
Cyanide Hydroxide Cyanide
HNO KOH KNO H2O
Nitric Potassium Potassium
acid Hydroxide nitrate
2HCl Ca(OH) CaCl H2O
Hydrogen Calcium Calcium
Chloride Hydroxide chloride
HF NaOH NaF H2O
Hydrogen Sodium Sodium
fluoride Hydroxide fluoride
Table10.1 acid-base reactions and the salts formed

5. 10.2 Some acids and bases are stronger than others
The stronger an acid, the more readily it donates hydrogen ions.
The stronger a base, the more readily it accepts hydrogen ions.

6. A nonelectrolyte B strong electrolyte C weak electrolyte
The pure water in this circuit is unable to conduct electricity because it contains practically no ions
Because HCl is a strong acid, nearly all of its molecules break apart in water, giving a high concentration of ions
Acetic acid, C2H4O2, is a weak acid and in water only a small portion of its molecules break up into ions

7. 10.3 Solutions can be acidic, basic or neutral
In water, equal amount of H3O+ and OH- (10-7M) (neutral solution)
In acidic solution, more H3O+ than OH-
In basic solution, more OH- than H3O+

8. Acidity 酸性 (and basicity 碱性) can be scaled by pH value
pH = -log[H3O+]

9. 10.4 Rainwater is acidic and ocean water is basic
The main sources of acidic rainwater are CO2 and SO2.
The damage of acidic rainwater depends on the local geology.
1. rain is acidified as it falls through the air
2. acid enters lake from rain
3. hydronium ions are neutralized by calcium carbonate released from limestone
2H3O++CaCO H2O+CO2+Ca2+
1.Rain is acidified as it falls through the air
2. acid enters lake from rain
3. hydronium ions concentration increases, with potential harm to the ecosystem

10. Carbon dioxide is absorbed and released
Ocean can absorb CO2
Carbon
dioxide
is absorbed
Carbon dioxide is absorbed and released
Ocean PH=8.2
Fresh-water lake PH<7

11. The concentration of CO2 in air has been increased, which is related to global warming
Fig10.18 Researchers at the Mauna Loa Weather Observatory in Hawaii have recorded increasing concentrations of atmospheric carbon dioxide since they began to collecting data in the 1950s.The chart left shows how the concentration of CO2 in the atmosphere has changed in the last 40 years

12. 10.5 Buffer solutions (缓冲溶液) resist changes in pH
Effective buffer solutions can be prepared by mixing a weak acid with a salt of the weak acid.
Fig10.19 Hydrochloric acid added to a solution
containing acetic acid and sodium acetate is
neutralized by the sodium acetate to form
Additional acetic acid
Fig Sodium hydroxide added to a
Solution containing acetic acid and sodium
Acetate is neutralized by the acetic acid
To form additional sodium acetate