Saturday, June 18, 2011

Restricting Chemical Sales

Police in Western Australia want to restrict stores selling some chemicals in a bid to "smash" clandestine drug laboratories according to a story in the Courier Mail today.
The list of chemicals being targeted includes drain cleaners, battery acid, and common lawn fertilizers.

Drain cleaners often contain sodium hydroxide, also known as caustic soda or lye. Sodium hydroxide, a white solid at room temperature, is a strong base that can cause chemical burns.
When sodium hydroxide is added to a blocked drain it dissolves in the water in the pipe and releases heat. This heat can melt the grease blocking the pipe. The sodium hydroxide also reacts with some of the fat in the pipe to form soap. This soap helps remove the grease blocking the drain.

Lead-acid batteries that are typically found in cars contain sulfuric acid, also known as vitriol. It is a strong acid that used in concentrations of around 30% w/w in battery acid. When sulfuric acid dissolves in water, heat is given off. Sulfuric acid can be neutralized by sodium hydroxide with the products of the reaction being water and sodium sulfate.

High-nitrogen content fertilizers can contain ammonium nitrate which is itself a white solid at room temperature and pressure. When ammonium nitrate dissolves in water it absorbs energy from the surroundings. Ammonium nitrate reacts with sodium hydroxide to produce ammonia gas, water and sodium nitrate.
Ammonia is a colourless gas with a pungent odour at room temperature and pressure. "Household ammonia", sold as a cleaning product for ovens, glass, porcelain and stainless steel, is a solution of ammonia in water. The concentration of this basic solution varies from 5% w/w to 10% w/w.
Ammonia is used to make many pharmaceuticals.

Reference
http://www.couriermail.com.au/news/national/police-bid-to-restrict-chemical-sales/story-e6freooo-1226077611068

Link
Further Reading
Naming Ionic Compounds
Writing Ionic Formula
Definitions and Properties of Acids and Bases
Enthalpy Change
Concentration: Percent by Mass
Concentration: Molarity


Study Questions
  1. Give the chemical formula for the following compounds:
    • sodium hydroxide
    • sulfuric acid
    • sodium sulfate
    • ammonia
    • ammonium nitrate
    • sodium nitrate
    • water
  2. Draw up a table with the headings, acidic, basic, neutral. Place the compounds listed above in the appropriate places in the table.
  3. Draw up a table with the headings ionic and covalent. Place the compounds listed in question 1 in the appropriate places in the table.
  4. Define the terms exothermic and endothermic.
  5. Write an equation to show sodium hydroxide dissolving in water. Include the energy term. Is this reaction exothermic or endothermic?
  6. Write an equation to show sulfuric acid dissolving in water. Include the energy term. Is this reaction endothermic or exothermic?
  7. Write an equation to show ammonium nitrate dissolving in water. Include the energy term. Is this reaction endothermic or exothermic?
  8. Convert the following percent by mass concentrations to concentrations in mol/L
    • 30% w/w aqueous sulfuric acid solution
    • 5% w/w aqueous ammonia solution
    • 10% w/w aqueous ammonia solution
  9. Write balanced chemical equations for each of the following:
    • the neutralization of sulfuric acid by sodium hydroxide in aqueous solution
    • ammonium nitrate reacts with sodium hydroxide in solution
  10. Write an equation to show how sodium hydroxide can react with a fat to produce soap.
  11. Explain how soap can clean up built up grease in your drain.
  12. A student found a container of solution in the family's garage. it is believed to be either household cleaner or battery acid. Describe tests that you could conduct in order to determine what solution is in the container. What safety precautions would you take when conducting these tests?

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