Procedure . Get about 20 mL of 0.05 M Fe3+ (this will be labeled and used as the "prototype") and 30 mL of 0.0002M KSCN in labeled 50 mL beakers. 2. Label 3 other beakers "Solution 1", “Solution 2", and "Solution 3" which will be produced from Dilution 1, 2, and 3. 3. Dilution 1 to make Solution 1. a. Rinse a 10 mL graduated cylinder with a few mL of 0.05M Fe* Solution, and discard the solution in the sink b. Rinse a 25 mL graduated cylinder with a few mL of water, and discard the solution in the sink c. Measure 10.00 mL of 0.05 M Fe³+ solution in the 10mL graduated cylinder, then pour it into the 25 mL graduated cylinder. d. Add water to dilute to 25.0 mL e. Pour solution from 25 mL graduated cylinder into the beaker labeled Solution 1 4. Dilution 2 to make Solution 2. a. Rinse the 10 mL graduated cylinder with a few mL of Solution 1, and discard the solution in the sink. b. Measure 10.00 mL of Solution 1 in the 10 mL graduated cylinder, then pour it into the 25 mL graduated cylinder. c. Add water to dilute to 25.0 mL d. Pour solution from 25 mL graduated cylinder into the beaker labeled Solution 2 5. Dilution 3 to make Solution 3. a. Rinse the 10 mL graduated cylinder with a few mL of Solution 2, and discard the solution in the sink. b. Measure 10.00mL of Solution 2 in the 10 mL graduated cylinder, then pour it into the 25 mL graduated cylinder. c. Add water to dilute to 25.0 mL d. Pour solution from 25 mL graduated cylinder into the beaker labeled Solution 3 6. Reaction (Solution 3) a. Rinse the 10 mL graduated cylinder with a few mL of Solution 3, then discard the solution from this rinse in the sink b. Add 5.00 mL of solution 3 to the 10 mL graduated cylinder. c. Add 5.00 mL of.0002 M KSCN to the 10 mL graduated cylinder (total volume 10.00 mL) d. Pour some of the mixture into a clean, dry cuvette so that the cuvette is at least half full. Pour the rest into a test tube for backup. Keep track of which reaction went into this cuvette, but do not label it, as a label will interfere with the spectrophotometer. 7. Reaction (Solution 2) a. Rinse the 10 mL graduated cylinder with a few mL of Solution 2, then discard the rinse solution in the sink b. Add 5.00 mL of solution 2 to the 10 mL graduated cylinder. c. Add 5.00 mL of .0002 M KSCN to the 10 mL graduated cylinder (total volume 10.00 mL) Page 50 d. Four some of the mixture into a clean, dry cuvette so that the cuvette is at least half full. Pour the rest into a test tube for backup, Keep track of which reaction went into this cuvette, but do not label it, as a label will interfere with the spectrophotometer. 8. Reaction (Solution 1) a. Rinse the 10 mL graduated cylinder with a few mL of Solution 1, then discard the rinse solution in the sink b. Add 5.00 mL of solution 1 to the 10mL graduated cylinder. C. Add 5.00 mL of.0002 M KSCN to the 10 mL graduated cylinder (total volume 10.00 mL) d. Pour some of the mixture into a clean, dry cuvette, and pour the rest into a test tube. Keep track of which reaction went into this cuvette, but do not label it, as a label will interfere with the spectrophotometer. 9. Reaction (Prototype) a. Rinse the 10 mL graduated cylinder with a few mL of 0.05 M Fe, then discard the rinse solution in the sink b. Add 5.00 mL of 0.05 M Fe to the 10mL graduated cylinder. c. Add 5.00 mL of.0002 M KSCN to the 10 mL graduated cylinder (total volume 10.00 mL). d. Pour some of the mixture into a clean, dry cuvette, and pour the rest into a test tube. 10. Read and record the absorbance for each of these solutions. The prototype data goes on item A on the data page(at the top, one a line alone) and used to calculate the slope, m. The other solutions, 1-3, go on item D in the table provided. If the absorbances for the more concentrated solutions are higher and spaced by reasonable amounts from those with lower concentrations, then the solutions may all be discarded in the drain. Calculations 1. After using the prototype data to get m-slope, use this slope and the absorbance for each to calculate the [FeSCN2"] for each solution mix 1,2, and 3. 2. Subtract the [FESCN2 ] from the [Fe ] and [SCN] to determine the remaining amount of [Fe] and [SCN] and put this value on the last block of the lines in the tables. 3. Calculate the equilibrium constant for this reaction. 4. Finish the statistical analysis and other questions.
1. a) "Solution 1" is made from the addition of water to a portion of the 0.0500 M Fe3+ " prototype" solution. Water is added to "prototype" as stated in the "dilution one" lab step to create a more dilute Fe3+ solution called "Solution 1". If you follow the lab procedure in the dilution one lab step, what will be the resultant molarity of Fe3+ in "Solution 1"?
b) The Fe3+ "Solution 2" is made by using water to dilute the Fe3+ "Solution 1". Using the dilution scheme described in your lab manual as "Dilution 2" to calculate the new, even more dilute, Fe3+ level in "Solution 2". Remember to use the molarity for the Fe3+ in " Solution 1 as your initial molarity for this calculation (see your value from question above).
c) The Fe3+ "Solution 3" is made by using water to dilute the Fe3+ "Solution 2". Using the dilution scheme described in your lab manual as "Dilution 3" to calculate the new, even more dilute, Fe3+ level in "Solution 3". Remember to use the molarity for the Fe3+ in " Solution 2 as your initial molarity for this calculation (see your value from question above).
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