CHEMICAL KINETICS QUANTITATIVE FLAME TEST: DETERMINING UNKNOWN SODIUM CONCENTRATION Methodology: A. Standardization of NaOH Solution 1. Clean a burette with detergent, including its inside walls. Then rinse it thoroughly with tap water. Rinse the tip of the burette by opening the stopcock and letting the water ?ow. Rinse the inside walls by rolling the burette on your hands. The burette is clean when water droplets do not cling to the inner surface. 2. Obtain about 75 mL of the NaOH solution in a clean and dry 100 mL beaker then cover with a watch glass. 3. Rinse the burette with three portions (about 5 mL) of the NaOH solution. Discard NaOH rinsate into the sink with running water. Don 't forget to rinse the inner walls of the burette with the NaOH solution. 4. Fill the burette with NaOH to slightly above the zero mark. 5. Remove the air bubbles from the tip ofthe burette by draining the NaOH into a small beaker. Read the NaOH level to within +f— 0.0] mL and record this value as the initial NaOH reading. 6. Place a clean and dry 100 mL beaker in an analytical balance. Add 0.2530; g (x can be any num ber)of KHP (potassium hydrogen phthalate). Record the weight of the KHP. (PERFORM STEP 6-12 IN TRIPLICATE) 7. Dissolve all the KHP with distilled water by adding about 25 mL of distilled water to the beaker with constant stirring. Transfer the KHP solution into a clean 250 mL Erlenmeyer ?ask. Rinse the beaker and the stirring rod and transfer the rinsate to the ?ask to make sure all of the acid (KHP) has been completely transferred. Do this for trials 1-3. 8. Add 3 drops of phenolphthalein indicator to the acid solution in the Erlenmeyer ?ask. 9. Place the ?ask containing the acid solution and indicator under the burette. A white piece of paper placed under the ?ask will aid in the color detection. By opening the stopcock, add NaOH from the burette to the ?ask while swirling until the color of the solution in the ?ask turns faint pink. There should be a one-drop difference between when the solution is colorless and when it is pink. The color of the solution should remain faint pink even after continuous swirling. If too much base is added and the solution turns ?tchsia pink, discard the solution and repeat the titration. 10. When the proper end point is reached, read and record the final NaOH reading.

ll. Discard the contents of the Erlenmeyer ?ask into the sink with running water. [2. Calculate the molarity of the NaOH from the titration. B. Preparation of NaOH Standard Solutions From the standardized NaOH stock solution, prepare 100 mL of the following NaOH standard solutions through serial dilution. i. 0.0001 M ii. 0.0005 M iii. 0.001 M iv. 0.004 M v. 0.007 M vi. 0.01 M vii. 0.05 M viii. Unknown 1 8: 2 1. Pour a small amount of the standardized NaOH solution in a beaker. 2. Pipet the calculated volume of NaOH and transfer into a properly labeled 100 mL volumetric ?ask. 3. Add distilled water into the volumetric ?ask until the 100-mL mark. 4. Mix the solution for homogenization. C. Flame Test 1. Arrange the experiment as shown in the Figure. The distance between the ?ame and the camera must be fixed (around 40 cm). Do not change the focus and settings Ofthe camera for the entire experiment. The test needs two people to perform: one to spray the sample and one to acquire the video. 2. Start by recording a video of the ?ame without spraying anything. Apply this procedure in duplicate. 3. Proceed with the blank test by spraying distilled water into the ?ame. Record a video of the ?ame. Apply this procedure in duplicate. 4. Repeat Step C.3. using the prepared standard and unknown solutions.

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