Changing Freezing and Boiling Points

Do you know what is inside the strange building shown in this photograph? The building is used to store salt that is spread on the road when weather conditions are below the freezing point of water. What effect will the salt have on icy roads? Why store the salt in a building?


This truck removes snow and spreads salt. How does spreading salt on roads reduce accidents?


A solution of antifreeze is used to fill car radiators. It lowers the freezing point of the water in the radiator of the car. It also raises its boiling point and reduces corrosion. Why are the properties of this solution useful to motorists? Why isn’t salt used instead?

Separation Science at the FBI

Questions

1. What are the two types of chromatography mentioned in this reader? Use an encyclopedia, other library resources, and the Internet to find out more about these and other chromatography techniques.

2. Luminol is a chemical used by forensic scientists to reveal traces of blood not readily visible to the human eye. Do a search on the Web site http://www.howstuffworks.com to find out how Luminol works.

Getting Taken to the Cleaners

Questions

1. Why do people who own washing machines still go to the dry cleaners?

2. Can you suggest two advantages of recycling the solvents used in the dry-cleaning process?

3. Heat generally causes materials to expand. If this is true, why do some fabrics shrink when washed?

Separating Solutions and the Salty Sea

Why is the sea saltier than rivers?


What is desalination?


What do the Salton and Aral Seas have in common?


What environmental problems do they have?

It is widely believed that the term "salary" was derived from the Latin word for salt. Based on what you read in this article, why might this be true?