1. Acids, Bases & Salts

2. Introduction Chemicals may be classed as acids or bases.
Things that are neither acids nor bases are neutral.
Neutral solution = pure water
pH measures how acidic or basic a solution is.

3. Acids
Acid – any compound that produces hydrogen ions in solution (ex: hydrochloric acid, lemon juice, vinegar)
Strong acids can burn skin and eyes and even dissolve metals!
Ex: Hydrochloric acid
HCL  H+ + Cl-
When acids are in water, the H+ molecule breaks loose

4. Base
Base – hydroxide (OH-) is dissolved in water (Ex: milk, baking soda, drain cleaner)
Strong bases can burn skin & eyes
Bases react more easily with protein than with metal and are often used for cleaning
Ex: Sodium Hydroxide
NaOH  Na+ + OH-

5. Neutralization
Neutralization - Process of reacting an acid and a base to produce a neutral solution
Ex: H+ + OH-  HOH (or H2O)
If the quantities of acid and base are right, all the H+ and OH- combine and there will be no excess  then the solution will become neutral

6. Salts
Salts – compounds produced by the neutralization between an acid and base
Ex: Hydrochloric acid and sodium hydroxide
HCl + NaOH  Na+ + Cl- + HOH

7. How do we determine the difference between and acid and a base??

8. pH Scale
pH – a unit of measurement that indicates the concentration of hydrogen ions (H+) in a solution
p - stands for potential
H – stands for Hydrogen
pH = the potential of a substance to attaract hydrogen ions
pH Scale goes from 0-14
0-6 = Acidic
7 = Neutral
8-14 = Basic

9. 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

10. pH Scale 0--------------7---------------14 Acid Neutral Base
If the solution has a ……
Acid Neutral Base
(*the closer to the end of the scale, the stronger the solution is)
H+ Ion Concentration pH
Acid or Base or Neutral
High Concentration of H+
Low pH (0-6)
Acid
Low Concentration of H+
High pH (8-14)
Base 7
Neutral

11. Indicators
Indicators – a substance that changes color when the pH goes above or below a certain value
Types of Indicators –
Litmus paper
Methyl Orange
Phenolphalein
pH Paper
Digital pH meters

12. 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.
How to use pH Paper:
Dip the pH strip into the solution
The pH paper will change color as it reacts to the pH of the solution
Match the color of the strip to the color key on the cover of the container

14. Why is pH important? Fish can’t live if the pH is too high or too low
Soil has to be in a certain pH range for plants to grow and stay healthy.

15. Why is pH important?
Water that has too high or low pH contains harmful dissolved chemicals.
Water plant operators keep a careful watch on the pH of our drinking water, to keep it safe.
Heavy metals, such as lead, react to changes in pH. Environmental regulations require drinking water to remain within a specific pH range to prevent lead and other metals from dissolving out of pipes and containers and entering the water.