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AoS 2 How substances in water are analysed.

Ecolinc
Full Day
Book Program
Year Levels
Unit 2 — What makes water such a unique chemical?

Background

Water quality tests are conducted regularly by water agencies to ensure that drinking water is safe, and to monitor the health of waterways as it may be used for irrigation and by wildlife. A variety of parameters may be measured to provide an overall water quality rating including: pH, salinity, temperature, dissolved oxygen, nitrogen (as nitrates), phosphorus (as phosphates), turbidity and metal concentration. The Ecolinc wetland is a constructed wetland reliant on rainfall and resultant stormwater. The wetland supports a variety of animal and plant life including the endangered Growling Grass Frog. As an ephemeral wetland, the waterway occasionally dries up.

Metals play an important role in water chemistry and water quality. Some metals are toxic at high concentrations while others play an essential role in water systems. An atomic absorption spectrometer (AAS) may be used to detect the concentration of ~70 metals at trace levels even in the presence of other elements at much higher concentrations. Detection limits in the parts per million range are well within the capabilities of modern instruments. Atomic absorption spectroscopy relies entirely on the absorption of energy by valence electrons of ground state atoms and was discovered by Australian physicist Sir Alan Walsh in 1953.


Prior Knowledge

No prior knowledge required.


Learning Intentions

In this program student’s will:

  • Investigate the water quality of six water samples using a variety of instruments to measure a number of water quality parameters.
  • Comment on results by comparing with published standards.
  • Complete a Risk Assessment for one chemical test.
  • Investigate the sodium concentration of the six water samples using the AAS to measure the absorbance of sodium standards.
  • Undertake qualitative analysis of metals in water using flame tests.
  • Plot a calibration curve and use to determine the concentration of sodium in the water samples.

Activities

  • Test each water sample for specific parameters.
  • Prepare sodium standards and use the AAS to measure the absorbance of these standards and water samples.
  • Record results in the data tables provided and complete any calculations required.
  • Interpret results by completing the worksheet.

Learn Online

Ecolinc Learn Online is a virtual outreach learning management system (LMS) offering interactive online courses for students and teachers. These courses can be undertaken either as a pre-visit, post-visit or stand-alone.

Students are encouraged to do the pre-learning course on Ecolinc Learn Online called Safe Labs prior to coming to Ecolinc. In this course students will cover all the necessary aspects of laboratory safety during their time at Ecolinc. When planning any work in a laboratory the risk of exposure to laboratory hazards is an important consideration. This course is part of Ecolinc’s risk minimisation for student safety.


VCE links

Outcome 2

  • On completion of this program, students should be able to measure amounts of dissolved substances in water and analyse water samples for salts.
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