An activity that allows you to introduce the concept of acids and bases through inquiry. This activity can be a lot of fun. Also to introduce the concept of neutralization.

1. Acids
and
Bases

2. Acids and bases in the real
world.
 Batteries
 Pools
 Household cleaners
 Milk
 Sharpies
 Stomach acid/blood(base)

3. What are acids and bases?
 Brnsted-Lowry acids and bases
 Acids donate H+ ions to another ion or
molecule, which acts as a base.
 Bases accept H+ ions from acid
compounds.

4. So what does this look like in
equation form?
 HCl + NaOH ---> H2O+ NaCl
 Acid Base water Salt

5. pH and what it means.
 A rating of 0 on the pH scale indicates a
substance that is virtually pure acid, while
a 14 rating represents a nearly pure base.
A rating of 7 indicates a neutral
substance.
 pH just defines the concentrations of
Hydrogen ions(H+) and hydroxide(OH-).

6. Aqueous Solutions
 An aqueous solution is a acid or base in
water. For example HCl poured into
water.
 What happens to the HCl?
 Does the water affect the pH?

7. Aqueous Solutions cont.
The chemical formula for
water is
H+ + OH-  H2O
Does water affect any acids
or bases when mixed?

8. So lets take a look at acids
and bases.
 Activity 1
 Color Changes with Acids and Bases
 You will be given three solutions
 Sodium Hydroxide
 Vinegar
 Cream of Tartar

9. Cont.
 You will also be given two indicators.
 BBT indicator
 Is naturally blue and when mixed with an acid
it will turn yellow
 Phenolphthalein
 Is naturally clear and when mixed with a base
it will turn pink.

10. Procedure
 1. Label 4 empty clear plastic punch cups
cream of tartar, detergent, vinegar, and
control.
 2. Carefully pour 2 tablespoons of
indicator solution into the control cup and
fill with water.
 3. Place the four labeled cups on a white
piece of paper and fill with two spoons full
of Lake Michigan Water.

11. Procedure cont.
 Students add acids and bases to the cups
 Cream of tartar
 Use the scoop end of the straw to scoop up a
small amount of cream of tartar.
 Add the cream of tartar to the cream of tartar
cup.
 Gently swirl to mix.
 Sodium Hydroxide
 Use a dropper and drop 3 or 4 drops of sodium
hydroxide into the cup. Add the Sodium
Hydroxide to the NaOH cup.
 Gently swirl to mix.
 Vinegar
 Use a dropper to add 2 or 3 drops of vinegar to
the vinegar cup.
 Gently swirl to mix.

12. Procedure cont.
 5. Students add the phenolphthalein
indicator to each cup.
 Only one cup should change color.
 6. Now add the excess control indicator
to the remaining mixtures that did not
change change.

13. So what were the
acids and bases?

14. Can you think of a way
to return the Yellow
indicator solution from
Activity 1 back to blue?

15. Activity 2: Neutralization
 what they might do to return the pink
indicator solution from Activity 1 back to
clear?

16. Neutralization
 What should you add to the yellow cream
of tartar solution to change the color back
to blue like the control?
 What should you add to the pink Sodium
Hydroxide solution to change the color
back to clear?
 Should you add a little bit of Sodium
Hydroxide or cream of tartar, or a lot at
once?
 What will you do if the color does not quite
change back to the original color after
mixing the powder into the indicator
solution?
 How will you know when the solution has
been neutralized?

17. Neutralization cont.
 Neutralize the cream of tartar solution and the
Sodium Hydroxide solution.
 Use a clean dropper to add a small amount
of Sodium Hydroxide to the cream of tartar
and swirl. Observe the color. If needed,
continue this process until the solution returns
to blue.
 Use a different clean toothpick/dropper to
add a small amount of cream of
tartar/vinegar to the Sodium Hydroxide
solution and swirl. Observe the color. If
needed, continue this process until the
solution returns to clear/pink.

18. Disscussion
 Were you able to return the yellow and
pink indicator solutions back to their
original colors?
 What could you have done if the yellow
indicator turned pink instead of blue?
 What could you have done if the pink
indicator turned yellow instead of clear?
 How would you neutralize the vinegar
solution?
 Can a base neutralize an acid?
 Can an acid neutralize a base?

19. Yesterday
So the day before we looked at
neutralizing acids and bases with
each other correct?
So today we are going to look at
precise amounts of acid and base
to neutralize the reaction.

20. So what I would like you to do today is to pick
either the vinegar or the Sodium hydroxide to
neutralize.
Remember which indicator you
need to use.
If you choose vinegar what
indicator do you need to use?
If you choose Sodium hydroxide
what do indicator do you need?

21. Now choose one to start with
before we continue.
Vinegar Sodium
Hydroxide

22. Colors?
What color will you start
and end with for vinegar?
What color will you start
and end with for Sodium
Hydroxide?

23. Procedure
Vinegar
 Do two or three
trials ranging from 2
to 10 drops of
vinegar. Then
neutralize with
Sodium Hydroxide.
 Keep track of the
drops you use.
 Sodium Hydroxide
 Do two or three
trials ranging from
15 to 30 drops of
sodium hydroxide.
Then neutralize with
vinegar.
 Keep track of the
drops you use.

24. Discussion
 What is the relationship between
the amount of acid in the solution
and the number of drops of base it
takes to return the solution back to
neutral?

25. Results
The results come out to be for
every about every three drops
of vinegar you need about 10
drops of Sodium Hydroxide.