Question

In my organic chemistry lab we are performing a gas chromatography experiment and I need help with our prelab assignment, thanks!

Question 3 1 pts If compound A elutes (comes off) a GC column earlier than compound B in a temperature gradient GC run. What can be inferred about their respective boiling points? Compound A probably has a lower boiling point than that of compound B. Compound A and B have the same boiling point. Elution time does not correlate to boiling point in any significant way. Compound B probably has a lower boiling point than that of compound A. Question 4 1 pts Why is it important for the condenser to have water flowing upward through it? To ensure that the water flow is fast enough to keep the glass cool. To ensure the tube is completely full which maximizes the transfer of heat. O None of the above. To ensure the tube has an airgap, to allow the condenser to equilibrate with the vapor.

Answer 1

3) GC is based on the boiling I point differences of the molecule. A molecule which has higher boiling point elutes at the last and hence shows heak at the end. While a low molemlar weight compounds comes down (elutes) fast. Conclusion: A Compound A has a lower boiling point that B. (4) It is important fro water to flow upward in a condenser so as to reach water completely up to the end which provides efficient cooling Conclusion: 6 → To ensure the tube is completely full which maximises transfer of heat and thereby cooling the vapour.