1. What is pH?

2. Acids and Bases
Some of our favorite foods make our tongue curl up because they are SOUR.

3. Bitter!
Some foods have a “bite” of their own because they’re somewhat bitter.
WHY?

4. Acidic/Basic There is a scientific reason for this:
These foods are either acidic or basic.
Other substances besides foods have these characteristics.

5. Acids and Bases Chemicals may be classed as acids or bases.
Things that are neither acids nor bases are neutral.
pH measures how acidic or basic a solution is.

6. Acids Often taste sour Strong acids can burn skin & eyes
Strong acids can dissolve metals
Examples:
Lemon juice
Vinegar
Car battery acid (dangerous!)

7. Bases Can taste bitter, sweetish, or salty
Strong bases can burn skin & eyes
Bases react more easily with protein than with metal; they are often used for cleaning
Examples:
Milk
Baking soda
Soap
Drain cleaner (dangerous!)

8. Some substances are not really an acid or a base: For example, pure water

9. Most Substances: Can be identified as either acidic or basic
Like the soil in our backyard.

10. pH Scale A scale that measures the acidity of a substance
“p” stands for power and “H” stands for hydrogen;

11. The pH Scale pH scale ranges from 0 -14
pH 7 is neutral; neither acid nor base
Pure water is pH 7
Low pH (0-6.9) = acid
High pH (7.1-14) = base
The closer to the ends of the scale, the stronger the solution is

12. How Do We Measure pH?
We measure pH by using special strips of paper called pH paper

13. How Does It Work?
The paper is treated with chemicals that change color to show the pH.
When the paper touches the substance being tested, it turns a specific color to tell if the substance is an acid or a base.

14. The pH Scale

15. The pH Scale Each pH unit is 10 times as large as the previous one
A change of 2 pH units means 100 times more basic or acidic
x10
x100

16. Neutralization Reactions
Neutralization reactions occur when an acid and a base react to form products that have a pH closer to 7, than the two reactants
The reactants are an acid and a base
The products are a salt (ionic compound) and water

17. Predicting products of Neutralization Reactions
HCl (aq) + NaOH (aq)  H2O (l) + NaCl (aq)
The sodium ion and the hydrogen ion switch places….forming NaCl and H-OH (water)
This is a double displacement reaction!!

18. Predict the products of the following reactions and balance
__ HNO3 + __ NaOH 
__ HCl + __ Ca(OH)2 
__ H2SO4 + __ LiOH 
__ HNO3 + __ Ba(OH)2 
__ HCH3COO + __ Al(OH)3 

19. Predict the products of the following reactions and balance
1 HNO3 + 1 NaOH  1NaNO3 + 1 H2O
2 HCl + 1Ca(OH)2  1 CaCl2 + 1 H2O
1 H2SO4 + 2 LiOH  1 Li2SO4 + 2 H2O
2 HNO3 + 1 Ba(OH)2  1 Ba(NO3)2 + 2H2O
3 HCH3COO + 1 Al(OH)3 
1 Al(CH3COO)3 + 3 H2O

20. Homework Pg 275 # 2-5 Pg 281 # 2, 3, 5, 7 Chapter 7 review:
Unit 1 Review pg # 1-57

21. Other bases….. Some bases do not contain an OH and yet are basic!
These include
Metal oxides, eg. CaO, MgO
Carbonates eg. CaCO3, (chalk) NaHCO3 (baking soda)