1. Shawn Bailey 4-15-11 Chemistry
Acids vs. Basics
Shawn Bailey
Chemistry

2. The pH scale measures how acidic or basic a substance is
ranges from 0 to 14
A pH of 7 is neutral (water serves as a control)
A pH less than 7 is acidic, and becomes more acidic as it approaches 0
A pH greater than 7 is basic, and becomes more basic as it approaches 14
It’s a logarithmic scale, meaning that:
anything less than 7 is 10 times more acidic then the number preceding it
Anything above 7 is 10 times more alkaline (basic) then the number preceding it

3. The pH scale Principle
the pH value indicates the concentration of H+ and OH- ions in an aqueous solution.
H+ ions make a substance acidic
OH- ions make a substance basic
H+ ion concentration and pH relate indirectly
As pH increases, the concentration of H+ ions decreases, and the substance becomes less acidic
OH- ion concentration and pH relate directly
As pH increases, the concentration of OH- ions also increase, and the substance becomes more basic

4. Acids
Compounds that produce H+ ions or H₃O+ ions when dissolved in water
Common Name
Chemical Name
Chemical Formula
pH value
Vinegar
Acetic Acid
CH₃COOH
2.4 – 3.4
Lemon
Citric Acid
C₆H₈O₇
2.3
Apple Juice
Malic Acid
C₄H₆O₅
2.9 – 3.3
Stomach Acid
Hydrochloric Acid
HCl
1 – 3
Grapes
Tartartic Acid
C₄H₆O₆
3.5 – 4.5

5. Alkalines (Basic)
Compounds that produce OH- ions when dissolved in water
Common Name
Chemical Name
Chemical Formula
pH value
Baking Soda
Sodium Bicarbonate
NaHCO₃
8.0
Borax
Hydrous Sodium Borate
Na₂[B₄O₅(OH)₄]· 8H₂O
9.2
Limewater
Calcium Hydroxide
Ca(OH)₂
12.4
Lye
Sodium Hydroxide
NaOH
14.0
Milk of Magnesia
Magnesium Hydroxide
Mg(OH) ₂
10.5

6. pH Indicators
Are halochromic, which means they change certain colors when added to certain pH levels
We can visually determine pH levels based off these color changes
Used in biology and chemistry
3 different types of indicators:
Universal Indicators
Complexometric Idicators
Redox Indicators

7. Common Acid-Base Indicators
Approximate pH range for color change
Color Change
Methyl orange
3.2 – 4.4
Red to yellow
Bromthymol blue
6.0 – 7.6
Yellow to blue
Phenolphthalein
8.2 – 10
Colorless to pink
Litmus
5.5 – 8.2
Red to blue
Bromcresol green
3.8 – 5.4
Thymol blue
8.0 – 9.6
Different Indicators are used for different substances, depending on their pH levels.
Methyl orange and bromcresol green are used to test for acidity because their ranges are 3.2 – 4.4 and 3.8 – 5.4
Thymol blue and phenolphthalein are used to test for a base because their ranges are 8.0 – 9.6 and 8.2 – 10
Bromthymol blue are used to test for neutral substances because its range is 6.0 – 7.6
Chart Found in Reference Table M

8. Neutralization
A double replacement reaction where an acid and a base reacts to produce a salt and some other substance, usually water
The H+ ions and OH- ions combine to produce the water, thereby neutralizing each other
Since Water is produced and has a neutral pH of 7, and H+ and OH- ions no longer exist, this explains why the pH values of the reactants are different the pH values of the products
Examples of neutralization:
HCL + NaOH  NaCl + H₂O
H₂SO₄ + 2NH₄OH  (NH₄)₂SO₄ + 2H₂O
2NaOH + H₂CO₃  Na₂CO₃ + 2H₂O
Ca(OH)₂ + H₂CO₃  CaCO₃ + 2H₂O

9. Overview of Acid Rain
rain that is unusually acidic due to elevated levels of H+ ions
The pH of regular rain is 5.7 and is slightly acidic, because CO₂ and H₂0 naturally form carbonic acid in the atmosphere
The pH of acid rain can be lower than 2.4 in industrial areas
Acid Rain is a harmful substance to Plants, Animals, and Water Sources, and even wears away buildings
Occurs in two forms:
Wet deposition (acidic precipitation)
Dry deposition (acidic gases and particles)

10. Acidification: Formation of Acid Rain
Acid Rain is formed when gases such as SO₂, CO₂ and NO₂ are released into the atmosphere and are converted to sulfuric, carbonic, and nitric acid
These are given off through forms of pollution, the main source being the burning of fossil fuels, as well as volcanic eruptions and wildfires
Formation of Carbonic Acid: H₂CO₃
CO₂ + H₂O  H₂CO₃
Formation of Nitric Acid: HNO₃
NO₂ + OH  HNO₃
Formation of Sulfuric Acid: H₂SO₄
SO₂ + OH  HOSO₂
HOSO₂ + O₂  HO₂ + SO₃
SO₃ + H₂O  H₂SO₄

11. Impact on Soil and Forests
harms vegetation by changing soil chemistry
exposure to acid rain leads to the loss of Ca, Mg, and K, important nutrients in soil
Acid Rain is more effective on the forest because of their sensitive soils
High levels of nitrogen lowers the soils capacity to hold other nutrients, which are washed
nitrogen saturation has effected: northeastern forests, the Colorado Front Range, and mountain ranges near Los Angeles, California.
Nutrient-poor trees are more vulnerable to climatic extremes, pest invasion, and the effects of other air pollutants, such as ozone

12. Impact on Birds freshwater acidity harms migratory birds
decline of the North American black ducks was caused by lack of food supplies in acidified wetlands
ducklings are 3 times more likely to die before adulthood in acidic waters
Snails can’t form shells because of Ca depletion
songbirds that get most of their calcium from the shells of snails die
defective eggs are laid and the chicks don’t hatch or have bone malformations
Decline in wood thrush population
Lack of nutrition due to Ca depletion
ingesting high levels of metals due to acidic soils
Declining wood thrush populations were most pronounced in the higher elevations of the Adirondack, Great Smoky, and Appalachian mountains.

13. Impact on Water Sources
Acid rain runs off into or falls directly on aquatic habitats
Normal pH levels of 6-8
Lakes and streams become acidic when the water itself and its surrounding soil cannot buffer the acid rain enough to neutralize it
Acid rain releases Al from soils into lakes and streams
aluminum is highly toxic to many species of aquatic organisms
Little Echo Pond in Franklin, New York is considered very acidic, with a pH of 4.2
harm or kill fish, reduce population, lead to extinction, decrease biodiversity
low pH levels and high Al levels are toxic to fish
Fish that don’t die weigh less and are smaller, making them unable to compete for food and habitat
Animal sensitivity to pH varies
Usually the young are more sensitive and die first
most fish eggs can’t hatch at a pH level of 5
As pH levels get lower, some adult fish die