Biology help needed

  

1. Calculate the volume of 1 M NaOH needed to prepare 10.0 mL of a 0.10 M solution.

2. Calculate the volume of 1 M HCl needed to prepare 10.0 mL of a 0.10 M solution.

2

Chemistry of Life: pH and Buffers
Student Name
Date

Data

Activity 1

Calculate the volume of 1 M NaOH needed to prepare 10.0 mL of a 0.10 M solution.

Calculate the volume of 1 M HCl needed to prepare 10.0 mL of a 0.10 M solution.

Data Table 1

Initial pH

pH after 1 drop 0.1M HCl

pH after 10 drops 0.1M HCl

pH after 1 drop 0.1M NaOH

pH after 10 drops 0.1M NaOH

Water

pH 4 buffer

pH 6 buffer

pH 8 buffer

In Activity 1, what happened to the pH of the water sample as 0.1 M HCl was added? How did this compare to what happened with addition of one drop of 0.1 M HCl to each buffer solution?

In Activity 1, why did the pH of the buffer solutions change after the addition of 10 drops of 0.1 M NaOH?

Activity 2

Activity 2

Data Table 2

Initial pH

pH after 1 drop 0.1M NaOH

pH after 2 drops 0.1M NaOH	pH after 4 drops 0.1M NaOH	pH after 8 drops 0.1M NaOH
100%
50%
25%
12.5%

In Activity 2, which concentration was the effective buffer? Explain what happened chemically as the buffer became more dilute.

Explain how the buffer could be diluted (in Activity 2), yet maintain the same pH. Hint: Reference the Henderson-Hasselbalch equation.

Photos

Photo 1

Insert photo of results of Activity 1.

The following should be visible in this photo:

·

Row and column labels

Photo 2

Insert photo of results of Activity 2.

The following should be visible in this photo:
· Row and column labels

© 2016 Carolina Biological Supply Company