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

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

### 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.

### 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