1. 1.2 Acids and Bases

2. Overview Properties and examples of pH Neutralization reactions Lab
Acids, bases, neutral solutions pH
The pH scale
Measuring pH
Neutralization reactions
Lab
Acid rain
Causes, impacts, and treatment

3. First... Brainstorm with your table partner:
Some properties of acids, bases, and neutral solutions
Examples of each solution
How they interact with one another, the environment, etc.

4. Properties of Acids Dissolve in water
Has more hydrogen ions (H+) than hydroxide ions (OH-) present
Taste sour, and can cause a stinging feeling
Fun fact: the liquid in your stomach is actually very acidic!

5. Properties of Bases Soluble in water
Has more hydroxide ions (OH-) than hydrogen ions (H+) present
Feel slippery and taste bitter
Fun fact: bases do not react with metals! This is what makes them such effective drain cleaners

6. Neutral Solutions
Neither acidic nor basic

7. pH: The Power (or Potential) of Hydrogen The pH Scale
pH is the measure of hydrogen ions, H+, in a solution
If the pH is less than 7 (i.e. 0-6) the solution is ACIDIC
If the pH is greater than 7 (i.e. 8-14) the solution is BASIC
A pH of 7 means the solution is NEUTRAL
The pH Scale

8. Strong vs. Weak Acids and Bases
Strong acids have a pH <2
Strong bases have a pH >12
Rule:
There is a 10-fold difference between the numbers on the pH scale
Meaning:
A pH of 2 will be 10 times more acidic than a pH of 3
A pH of 9 will be 10 times more basic than a pH of 8

9. Litmus Paper Measuring pH pH Paper pH Meter
Uses plant compounds called lichens
Tells us whether something is an acid or a base, does NOT tell what the pH is
Acids turn blue litmus paper red
Bases turn red litmus paper blue
pH paper (universal indicator)
Gives an approximate (i.e. whole numbers such as 1, 2, 3, etc.) reading of the pH
When dipping pH paper into a solution, the paper will change its colour-- this colour will indicate a specific pH!
pH meter (digital tool)
Gives an exact reading (i.e. decimal numbers) of the pH by measuring the ions present in a solution
pH Paper
pH Meter

10. Neutralization Reactions
Acids and bases can be neutralized by allowing them to react with each other
These reactions will form a salt and water (which are less harmful than the reactants!):
Strong acid + Strong base → Neutral
Strong acid + Weak base → Acidic
Weak acid + Strong base → Basic
Weak acid + Weak base → it depends on how weak the acid and base are relative to one another

11. Lab Time!

12. Video

13. Wrapping Up: Acid Rain Normal pH of rainwater is around 5.4
Slightly acidic because of CO2 which reacts with water to form carbonic acid
Acid rain usually has a pH of around 3-4
Industrial factories, coal-fired power plants, and vehicle emissions give off sulfur dioxide (SO2) and nitrogen oxides (NOx)
Water molecules in the air will react with these gases to produce sulfuric and nitric acids
These may all contribute to acid rain

14. Acid Rain Destroys lakes and streams
Kills aquatic organisms and plants
Buildings, and other structures such as statues deteriorate
How is this treated?
One method: Neutralization reaction!
Calcium hydroxide, Ca(OH)2 (aka ‘lime’), is added to lakes and streams
This reacts with the acids present to form a salt and water
Base Acid → Salt Water
If all of the acids and bases are used up, the solution becomes neutral!