L2
讲座
1. What is the lecture mainly about?
Observations that led to the discovery of supercritical fluids
Differences between the molecular structure of supercritical water and the molecular structure of supercritical carbon dioxide
Various processes used to change liquid water into a supercritical fluid
Ways in which certain supercritical fluids can be used
2. In the professor’s opinion, what use of supercritical water is especially promising?
Reducing the oxygen content of chemicals used in manufacturing processes
Purifying oxygen for use in manufacturing processes
Breaking down pollutants in wastewater
Transporting wastewater to storage facilities
3. What major problem with supercritical water does the professor mention?
Supercritical water damages the equipment that it is used with.
Supercritical water absorbs toxic substances from the equipment that it is used with.
Processes that use supercritical water waste a large amount of water.
Processes that use supercritical water take a long time to complete.
4. According to the professor, what is one advantage of supercritical carbon dioxide over supercritical water?
Carbon dioxide increases the efficiency of chemical solvents that are used to extract caffeine from coffee.
Carbon dioxide becomes a critical fluid at lower temperatures and pressures thar water does
Supercritical carbon dioxide typically contains fewer impurities than supercritica water does.
Supercritical carbon dioxide is more effective than supercritical water in destroying certain types of bacteria in coffee beans.
5. Why does the professor mention that even small changes in temperature or pressure result in changes in the properties of supercritical fluids?
To explain why supercritical fluids are difficult to control
To explain how supercritical fluids can be manipulated to perform specific tasks
To praise the technology that keeps the temperature and the pressure constant
To point out an aspect of supercritical fluids that is still not well understood
6. What does the professor imply would be one result of using supercritical carbon dioxide in manufacturing?
An increase in the cost of production
A shortage of water in communities near factories
A reduction in environmental pollution
The destruction of expensive manufacturing equipment
