L3
讲座
1. What is the lecture mainly about?
How cleaning products are made
How cleaning products work
Efforts to develop cleaning products that do not require water
Efforts to develop cleaning products that are environmentally friendly
2. What does the professor explain when he mentions intermolecular forces?
Why hot water works more efficiently with soap than cold water does
Why molecules sometimes break apart
Why some substances do not mix with each other
Why grease and oil attach easily to the skin
3. According to the professor, what is the defining characteristic of amphiphilic
molecules?
They create spheres that contain both water molecules and oil molecules.
They force water molecules and oil molecules to attract one another.
They arrange themselves in layers that are difficult to separate.
They are attracted to both water molecules and oil molecules.
4. Why does the professor mention the cloudy appearance of soapy water?
To explain what happens when certain kinds of oil dissolve in water
To make the point that soap does not cause oil to dissolve in water
To point out a way of checking whether a soap is functioning effectively
To emphasize that removing grease or oil requires both washing and thorough rinsing
5. According to the professor, how does detergent differ from soap?（多选题）
Detergent is not made from oils or fats.
Detergent molecules are not amphiphilic.
Detergent is more effective in hard water than soap is.
Detergent is less expensive to produce than soap.
6. What does the professor imply about the dishwashing detergents used in the
United States today when he says this:
They contain unacceptably high levels of phosphates.
They sometimes cause dishwashing machines to break down.
They cause more harm to the environment than earlier kinds of detergents did.
They do not clean as well as earlier kinds of detergents did.
