Acids, bases, pH and Neutralization Name ____________________________________

 

Purpose: To investigate the properties of acids, and bases and their effects on the pH.

Equipment:

Beaker graduated cylinder pH meter well plate

Materials: Vinegar 1.0 M NaOH 1.0 M HCl 1.0 M Oxalic acid, H2C2O4

Phenolphthalein Phenol Red Litmus solution

Procedure:

Part I Indicators

1.      In the well plate put one drop of HCl in 3 or the wells.

2.      Add on drop of phenolphthalein to one well, one drop of phenol red to another, and one drop of litmus to the HCl. Describe the colors of the mixtures.

3.      Clean and dry the well plate.

4.      Repeat steps 1-3 using NaOH in place of the HCl

5.      Clean and dry the well plate.

Part II pH

1.      Use the graduated cylinder and pour 20 ml of distilled water into the beaker.

2.      Take the cap off the bottom of the pH meter, turn it on and put the probe in the water. Record the pH of the water.

3.      Add one drop of HCl to the water, stir the mixture, and record the pH

4.      Add another drop of HCl to the water, stir the mixture, and record the pH

5.      Repeat step 4 until you reach a total of 5 drops of HCl.

6.      Clean and dry the beaker, and rinse the pH meter

7.      Use the graduated cylinder and pour 20 ml of distilled water into the beaker.

8.      Add one drop of NaOH to the water, stir the mixture, and record the pH

9.      Add another drop of NaOH to the water, stir the mixture, and record the pH

10.  Repeat step 4 until you reach a total of 5 drops of NaOH.

11.  Clean and dry the beaker, and rinse the pH meter

Part III Neutralizing HCl

1.      Use the graduated cylinder and pour 20 ml of distilled water into the beaker.

2.      Add five drops of HCl, and one drop of phenolphthalein to the water, stir the mixture, and record the pH.

3.      Add one drop of NaOH to the mixture, stir the mixture, and record the pH

4.      Add another drop of NaOH to the water, stir the mixture, and record the pH

5.      Repeat step 4 until you reach a total of 10 drops of NaOH. Note where the color changes.

6.      Clean and dry the beaker, and rinse the pH meter

Part IV Neutralizing Vinegar

1.      Use the graduated cylinder and pour 20 ml of distilled water into the beaker.

2.      Add five drops of Vinegar and one drop of phenolphthalein to the water, stir the mixture, and record the pH.

3.      Add one drop of NaOH to the mixture, stir the mixture, and record the pH

4.      Add another drop of NaOH to the water, stir the mixture, and record the pH

5.      Repeat step 4 until you reach a total of 10 drops of NaOH. Note where the color changes.

6.      Clean and dry the beaker, and rinse the pH meter

Part V Neutralizing Oxalic acid

7.      Use the graduated cylinder and pour 20 ml of distilled water into the beaker.

8.      Add five drops of Oxalic acid and one drop of phenolphthalein to the water, stir the mixture, and record the pH.

9.      Add one drop of NaOH to the mixture, stir the mixture, and record the pH

10.  Add another drop of NaOH to the water, stir the mixture, and record the pH

11.  Repeat step 4 until you reach a total of 10 drops of NaOH. Note where the color changes.

12.  Clean and dry the beaker, and rinse the pH meter, turn off the pH meter and put the cap back on.

Data Tables:

Part I

Indicator

Color in HCl

Color in NaOH

Phenophthalein

 

 

Phenol red

 

 

Litmus

 

 

Part II

Drops of HCl

pH

1

 

2

 

3

 

4

 

5

 

Drops of NaOH

pH

1

 

2

 

3

 

4

 

5

 

 

pH of water ______

 

 

 

 

 

 

 

 

 

 

Part III Part IV Part V

 

Neutralizing HCl Neutralizing Vinegar Neutralizing Oxalic acid

 

Drops of NaOH

pH

0

 

1

 

2

 

3

 

4

 

5

 

6

 

7

 

8

 

9

 

10

 

Drops of NaOH

pH

0

 

1

 

2

 

3

 

4

 

5

 

6

 

7

 

8

 

9

 

10

 

Drops of NaOH

pH

0

 

1

 

2

 

3

 

4

 

5

 

6

 

7

 

8

 

9

 

10

 

 

 

 

 

 

 

 

 


Analysis: Name ____________________________________

  1. Looking at Part I, why are litmus, phenolphthalein, and phenol red called indicators?
  2. Was the distilled water an acid a base or
  3. In Part II, did every drop of HCl have the same effect? Which one had the biggest effect?
  4. In Part II, did every drop of NaOH have the same effect? Which one had the biggest effect?
  5. Both the vinegar and the oxalic acid, both had the same concentration. Did the NaOH have the same effect on both? Look at the formula for the acid and see why?

Graphing:

Text Box: pHGraph the data in part III, part IV and part V, using a different color for each substance.