Question 5 A-D please. Please give brief explanations with the answers so I unde

Question

Question 5 A-D please. Please give brief explanations with the answers so I understand how to answer future problems. s A student injected an unknown mixture into a gas chromatograph and obsained the chromatogam shown below in the box. a)3pts) According to the chromatogram, which compound in the mixture injected on the GC has the highest boiling point? b) (8 pts) If you were to shorten the length of the column used, would the retention times be shorter or longer? e) (3 pts) If you increased the temperature of the oven, would the retention times be shorter or longer? d) (5 pts) Using the chromatogram, the student then started to make a table of data, but did not finish it. Complete the data table by calculating the percentage of each peak in the mixture and writing your answer in the appropriate box in the table below. % in Mixture Retention Time 4.2 min 8.1 min 8.6 min 12.6 min 13.6 min Area under peak 136 mm2 182 mm2 180 mm2 140 mm2 150 mm2 Peak

Explanation / Answer

5. For the given chromatogram

a. The highest boiling point fraction would elute at the end, that is it would have the highest retention time on the column. Therefore the compound with highest boiling point is compound E.

b. If the length of column is reduced, the compounds would spend lesser time on the column, therefore, the retention times would be reduced.

c. It the temperature of the oven is increased, the compounds would get lower time to spend on the column and they will be pushed out strongly. Therefore, retention times would reduce.

d. For the given table.

Find total area and then % of each compound in mixture = (individual area/total area) x 100

Total area = 788 mm^2

Peak     area (mm^2)          %in the mixture

   A              136                (136/788)100 = 17.26

   B              182                (182/788)100 = 23.10

   C              180                (180/788)100 = 22.84

   D              140                (140/788)100 = 17.77

   E              150                (150/788)100 = 19.03

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