Dr. Glaser's "Chemistry is in the News"
To Accompany Bruice, Organic Chemistry, 3/e.
Chapter 10. Reactions at an sp3 Hybridized Carbon II:
Elimination Reactions of Alkyl Halides; Competition Between
Substitution and Elimination.
Editorial Comments
I must have crossed the North Atlantic some 30 times or so in the splendid comfort of modern wide-body jets. My parents live in Germany and I go visit every year and sometimes twice. I have made the trip in every season and I have flown back and forth in daylight and at night. I always take a window seat so that I can see to the North. Depending on where the jet stream flows and what the weather is like, you get to see Greenland and Iceland and you can make out drifting icebergs even from 38,000 feet. Inevitably, you think about the legends of the Vikings and your mind starts imagining the hard and rough life these people must have led. Thanks to modern science, the mystery of the Vikings is becoming revealed.Questions
Question 1:
What is deuterium?
Answer 1:
The heavy isotope of hydrogen with mass 2. Deuterium contains on proton
and one neutron in its nucleus.
Question 2:
In chapter 10, you learned about the deuterium kinetic isotope
effects. Briefly explain the principle of the effect.
Answer 2:
See section 10.7 in the text.
Question 3:
Briefly describe how Barlow and co-workers employed a deuterium
kinetic isotope effect to measure temperature change in the Greenland ice
core over the past 700 years.
Answer 3:
The amount of deuterium in the ice indicates the temperature.
Ocean-borne water molecules made up of normal hydrogen evaporate at
slightly lower temperatures than do water
molecules made with the heavier deuterium.
But as the temperature goes up, more heavy hydrogen evaporates, eventually
precipitating out over Greenland.
Question 4:
Tritium is another isoptope of hydrogen. Tritium has mass 3. For a
reaction with a deuterium kinetic isotope effect of x>1, would the tritium
kinetic isotope effect be equal to x or would it be larger or smaller than
x.
Answer 4:
Larger than x.
Chemistry &
Society.
Question 5:
It did not take all that much of a climate change to make the viking
settlements collapse. A few cold summers, a lack of adaptation and an
inability to collaborate. Today, we face global climate change and the
consequences for our complex modern society are not clear. Will we be
able to adapt? The website of the
Intergovernmental Panel on Climate
Change highlights some of the challenges.