I need to answer the questions on the "RESULTS" section but i do not know how i can do them to find the concentration..
the first two pages are the procedure and the last is the section i need to answer.
The results for my experiment is as follows:
standard concentration
trial #1
trial #2
0.01
N/A
N/A
0.002
0.4
0.5
0.002
17.8
17.6
0.0004
39.8
39.5
0.0002
57.7
57.6
unknown ( MOUTHWASH)
29.6
29.4
Ecell = constant + 2.3RT[log(CMI +CM2 + )] (8 Equipment Fluoride selective electrode Polyethylene (plastic) beakers Magnetic stirrer Chemicals/Materials Total lonic Strength Adjustment Buffer Reference electrode-filling solutions: Orion equitransferent inner filling solution (#90-00-02) and 0.1 M NH4Cl for th outer solution of the double junction reference electrode Orion equitransferent filling solution for the single junction reference electrode. Procedure. Note: If students do not complete the experiment in one laboratory period they should put their solutions into well-labeled plastic bottles provided by the storeroom No solutions should be stored in glass containers due to fluoride etching of the glass. The sample must be returned to the storeroom for storage in the refrigerator for the wee The preparation of the working standards and all measurements must all be done on the same day Preparation of solutions 1. Dilute TISAB solution preparation. Dispense 100 mL of TISAB into a glass bottle and add 500 mL of distilled, de-ionized water. This solution will be your diluent in all the following solution preparations. Note: you will have only 100 mL spare for rinsing 2. Weigh 0.11 g of NaF to the nearest 0.1 mg into a beaker. Dissolve in 25 mL of de- ionized water. Transfer to a 250 mL glass volumetric flask, using de-ionized water to rinse. Dilute to volume with the diluted TISAB prepared in step 1. Calculate the exact molarity of this approximately 0.01 M NaF solution. 3. Pipet 10 mL of the 0.01 M solution into a 50 mL volumetric flask. Dilute to volume with the TISAB solution you prepared in step 1 above, to get a 0.002 M standard F- solution. Pipet 10 mL of the 0.002 M solution into a 50 mL volumetric flask, and dilute to volume with the TISAB solution you prepared, to get a 0.0004 M standard solution. 4. Using the 0.01 M stock solution in the 250 mL flask prepared in step 2, pipet 5 ml into a 50 mL volumetric flask and dilute to volume with the TISAB solution you prepared, to give a 0.001 M standard. Pipet 10 mL of this 0.001 M solution into a 50 mL volumetric flask and dilute to volume with the TISAB you prepared, to get a 0.000 standard. Page 5 Chemistry 5 Lab Manual
