Equipment:

- Data collection system

- Colorimeter

- Sensor extension cable

- Cuvette

- Beaker (3), 50-mL

- Syringe (3), 5-mL

- Watch glass, 4 in

- 0.1 M Sodium hydroxide (NaOH), 20 mL

- 1.2 x 10^-5 M Crystal violet, 20 mL

- Water, deionized, 30 mL

- Marking pen

- Kimwipes

Safety:

- In case of contact with skin, NaOH should be washed off with a large amount of water

Method:

1. Perform the experiment for each of the three runs as follows:

a. Deliver the water and sodium hydroxide solutions from the syringes into a clean cuvette

b. Start data recording

c. As quickly as possible, add the crystal violet solution to the cuvette, close the cuvette, invert it a few times, wipe it dry and clean and place it into the colorimeter

note: this should be done as quickly as possible to minimize the error arising from the delay of collecting data after mixing reactants

d. Immediately close the lid on the colorimeter and start data recording

e. Continue taking readings until the absorbance drops below 0.1

f. Stop data recording and clean the cuvette

g. For the next run, fill three syringes with the volume of liquids specified for the next trial and eliminate air bubbles, as before. Repeat the process for each of the next two runs.

2. Print the graph

3. Save your experiment and clean up according to your teacher's directions