1. Chapter 9 Section 1

2.  D12 - Explain the chemical composition of acids and bases, and explain the change of pH in neutralization reactions.

3.  What do you know about acids?  Can you name some acids?  Have you ever had lemonade? The juice of a lemon is an acid. So, this means that not all acids are alike, since you can safely drink lemonade, but not some other acids.

4.  Acids are compounds, which means that they are made of more than one type of element.  One of the elements is always HYDROGEN.  Properties: ◦ Taste sour ◦ They will turn blue litmus paper red ◦ They will conduct electric current ◦ They are corrosive ◦ They can sting in an open cut (weaker acids), or can damage your skin (stronger acids)

5.  When dissolved in water, they ionize.  This means that they split apart into the ions that make up the acid. H+ is ALWAYS formed. HCl H + + Cl -  One of the ions formed is the Hydrogen or H + ion  This can attach to the water molecules to form hydronium ions, H 3 O + H 2 0 + H + H 3 O +

6.  Strong acids ionize completely  Each molecule splits into its ions This makes a high concentration of hydrogen and hydronium ions in the liquid.  Weak acids do not ionize completely. This makes a lower concentration of hydronium ions in the liquid.

7.  Which of the following "molecular" pictures best represents a concentrated solution of the weak acid HA? AB

8.  Since there is complete ionization in water, this is a strong acid  An electrolyte is a liquid which can conduct electricity  Nitric Acid conducts electricity well, which means it is a strong electrolyte Nitric Acid

9.  This is an example of a weak acid  Weak acids do not conduct electricity well  This means that they are weak electrolytes Acetic Acid

10.  Acids are corrosive  They can damage living tissues  Acidic vapors can be harmful to eyes, mouth and lungs  Wear safety goggles, gloves, lab apron  Overall, be careful!

11. Bases!

12.  What do you know about bases?  Can you name some bases?  Do you use soaps or detergents? These are bases. Like acids, not all bases are alike.

13.  A base is a compound that increases the number of hydroxide ions (OH - ) when mixed with water.  Properties:  A basic solution tastes bitter.  A basic solution feels slippery.  They will turn red litmus paper blue.  Strong bases can also damage the skin.

14.  Like acids, when bases dissolve in water, they ionize.  This means that they split apart into the ions that make up the base. NaOH Na + + OH -  Note: Not all bases contain OH-. Some will react with water to form the hydroxide ion NH 3 + H 2 0 NH 4 + + OH -

15.  These work in a way that is similar to acids.  Strong bases cause a high concentration of OH - ions in the solution.  Weak bases cause a low concentration of OH - ions in the solution.

16.  Like acids, bases are corrosive and can damage living tissues  Wear safety goggles, gloves, and a lab apron!

17.  How do determine if something is an acid or a base?  How do we measure acid and base concentration or strength?

18.  Read pages 293-297.

20.  You can determine if a substance is an acid or base by using an indicator.  INDICATOR - A substance that changes color in the presence of an acid or a base.  Indicators measure the level of hydronium ions. This level determines if a substance is acidic or basic.

21.  Cabbage juice can be used as an indicator.  Litmus paper is a common indicator. Litmus strips are small pieces of paper that are treated with a substance that changes color when exposed to acids and bases  An acid turns blue litmus paper red  A base turns red litmus paper blue

22.  Litmus papers only function to let you know if a substance is acidic or basic.  They do not indicate strength or weakness of the solution.  To determine how acidic or basic a solution is, we use pH values.  pH is the measure of the concentration of hydronium ions in a solution.

23. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 A CIDIC B ASIC NEUTRALNEUTRAL The pH Scale

24. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 A CID B ASE NEUTRALNEUTRAL The pH Scale

26. Ion Concentration pH Scale 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Neutral Pure H 2 O [H + ] [OH - ] Acids Bases StrongerWeaker Stronger Acid – substance that produces H + ions in aqueous solution Base – substance that produces OH - ions in aqueous solution

27.  Lemon juice has a pH of 2.2. Is it an acid or a base?  Which does it contain, hydronium ions or hydroxide ions?

28.  Detergents such as Tide have a pH of about 10. Is Tide an acid or a base?  Which does it contain, hydronium ions or hydroxide ions?

29.  Seawater has a pH of 8.2. Is seawater an acid or a base?  Which does it contain, hydronium ions or hydroxide ions?

30.  The inside of your mouth has a pH of 7. Is it an acid or a base?

31.  How do you think we came up with the term “acid rain”?

32.  Read pages 297-300