1. Acids and Bases
Chapter 6.3 & 6.4

2. Mini-Project
Organize the following formulas into two groups with four formulas in each group:
HNO3, NaOH, H2SO4, H2CO3, Ca(OH) 2, KOH, H8PO4, Mg(OH) 2
One way to organize them into groups is:
Group One Group Two
HNO3 NaOH
H2SO4 Ca(OH) 2
H2CO3 KOH
H8PO4 Mg(OH) 2
Group One formulas represent acids.
Group Two formulas represent bases.

3. ACIDS Taste sour (lemon, vinegar) React with metal (corrosion)
React with carbonates (makes bubbles of CO2
Turns blue litmus RED
In Water forms Hydrogen ION
HCl H+ + Cl-
Water

4. BASES Taste Bitter (soap, tonic water) Feel Slippery (soap)
Turns Red Litmus Blue
In water, forms HYDROXIDE (OH-) ion
React with Acids to make water
NaOH Na+ + OH-
Water

5. Indicators
An Indicator is a chemical that turns colors under certain conditions.
Litmus paper is paper with the indicator litmus on it.
Litmus turns blue when in contact with a base
Litmus turns red when in contact with an acid
There are many different indicators
Bromthymol blue, universal, malachite green, etc.

6. Why are Some Solutions Acid & Others Base?
Acid solutions contain more H+ ions than OH- ions.
Base solutions contain more OH- ions than H+ ions.
Water is the standard for Acid/Base and is defined as NEUTRAL
Water has equal amounts of H+ and OH- ions

7. Arrhenius Model of Acids/Bases
Substance is an acid if it contains hydrogen and dissociation causes hydrogen ions to form in solution
Substance is a base if it contains a hydroxide and dissociates to produce hydroxide ions in solution

8. Bronsted-Lowry Model Acid is a hydrogen ion donor
Base is a hydrogen ion receptor
This is a broader definition than Arrhenius model because there are substances that cause donation or reception without having hydrogen in them.

9. Electrolytes Acids and Bases are ELECTROLYTES They ionize in water
They conduct electricity

10. Strong vs. Weak Weak Acids/Bases vs. Strong Acids/Bases
Strong acids/bases ionize completely
Weak acids/bases only partly ionize
Strong Bases are just as dangerous as Strong Acids
They react with most things they touch

11. More Concentrated vs. Dilute
Concentrated means lots of acid/base in a little bit of water
Dilute means a little bit of acid/base in a lot of water
Concentrated Acids and Bases are VERY Dangerous
They react quickly with many substances

12. Common Acids

13. Common Bases

14. Acid Rain
Acid rain comes from rain collecting gasses from the air to create acids:
Carbon Dioxide = carbonic acid
Sulfur oxides = sulfuric acid
Nitrogen oxides = nitric acid
Damages statues, buildings, kills forests, kills fish

15. pH Scale

16. pH pH stands for ‘per hydrion’
It measures the amount of hydrogen ions in solution
Water is defined as ‘neutral’
Water has one H+ and one OH- equal numbers
The concentration of H+ in water is 1.0 x 10-7
The pH of water is 7
A lower pH means MORE Hydrogen ions (Acid)
10-6 is Larger than 10-7
A higher pH means LESS hydrogen ions (Base)
10-8 is Smaller than 10-7
pH scale is a way of showing this relationship of hydrogen ions

17. pOH In water concentration of H+ = concentration of OH-
So [H+] = [OH-] = 1.0 x 10-7
Think about it:
H2O is the same as H-O-H which is H+ + OH-
So pOH of water is also 7
pH + pOH always equals 14, so
pH scale goes from 1 to 14

18. Common Items on the pH Scale

19. Neutralization Reactions

20. Acid-Base Reactions HCl + NaOH H2O + Na+ + Cl-
Neutralization reaction is a reaction between an acid and a base
Makes Water + Salt
Solution becomes Neutral (not acid or base)
NOTE: salt is a ‘category’ of chemicals, not always sodium chloride
HCl + NaOH H2O + Na+ + Cl-

21. Acid-Base Reactions Mg(OH)2 + 2 HCl → MgCl2 + 2H2O Note:
Cation from base (Mg) is combined with anion from acid (Cl)
The salt is MgCl2
The H+ and OH- always combine to form water

22. Acid-Base Titration
Acid/Base Titration is the stoichiometry of acid/base reactions.
Titration is a method for determining the concentration of a solution by using another solution of known concentration
Uses an INDICATOR to show when the acid/base reaction is complete (neutral)
Indicator is a chemical that changes color as determined by acid or base conditions
There are many indicators with different pH points.

23. Acid/Base Titration Curve

24. pH Indicators Name Acid Color pH Range of Color Change Base Color
Methyl violet
Yellow
Blue
Thymol blue
Red
Methyl orange
Bromocresol green
Methyl red
Litmus
Bromothymol blue
Phenolphthalein
Colorless
Pink
Thymolphthalein
Alizarin yellow R