ELECTROLYSIS OF SALT WATER
Unit: Salinity Patterns & the Water Cycle l Grade Level: High school l Time Required: Two 45 min.
periods l Content Standard: NSES Physical Science, properties and changes of properties in matter;
atoms have measurable properties such as electrical charge. l Ocean Literacy Principle 1e: Most of
of Earth's water (97%) is in the ocean. Seawater has unique properties: it is saline, its freezing point is
slightly lower than fresh water, its density is slightly higher, its electrical conductivity is much higher, and
it is slightly basic.
Big Idea: Water is comprised of two elements – hydrogen (H) and oxygen (O). Distilled water is pure
and free of salts; thus it is a very poor conductor of electricity. By adding ordinary table salt (NaCl) to
distilled water, it becomes an electrolyte solution, able to conduct electricity.
Ionic compounds such as salt water, conduct electricity when they dissolve in water.
Ionic compounds consist of two or more ions that are held together by electrical attraction. One of
the ions has a positive charge (called a "cation") and the other has a negative charge ("anion").
o Molecular compounds, such as water, are made of individual molecules that are bound together by
shared electrons (i.e., covalent bonds).
o What happens to salt when it is dissolved in water?
o What are electrolytes?
o How can we determine the volume of dissolved ions in a water sample?
o How are atoms held together in an element?
Knowledge and Skills
o Conduct an experiment to see that water can be split into its constituent ions through the process of
o Prepare and experiment with a 10% salt solution to better understand the process of ion exchange.
o Discuss and research the "softness" and "hardness" of water.
o Use the periodic table to identify elements and learn their characteristics.
o Define the difference between ionic and molecular compounds.
o Salt consists of sodi