Lecture 11

Lecture 11 - Lecture 11 Part 1- Data Synthesis and Cross...

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Anal Chem 251 Lecture 10 Analysis of Dissolved Oxygen 1 Lecture 11 Part 1- Data Synthesis and Cross Comparison Part 2 - Analysis of Dissolved Oxygen Lab: Prepare the Data Synthesis Report and Presentation Chapter 17: Problem 15 Corresponding Lab: Part 1 - Data Synthesis Presentation in the Lab Part 2 - Measurement of Dissolved O 2 - Amperometry
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Anal Chem 251 Lecture 10 Analysis of Dissolved Oxygen 2 Part 2 – Data Synthesis Presentation in the Lab • One of the instructors will e mail you all the data. • Pick one of the ions. • Prepare the report per instructions. • You may wish to prepare one or two overheads for your lab presentation.
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Anal Chem 251 Lecture 10 Analysis of Dissolved Oxygen 3 Why do We Measure Dissolved Oxygen (DO)? Fish and other marine organisms need oxygen. The oxygen they need is dissolved in water. The concentration of oxygen dissolved in water is an important indicator of water quality. Eutrophication, the process by which a body of water becomes rich in dissolved nutrients, thereby encouraging the growth and decomposition of oxygen-depleting plant life and resulting in harm to other organisms. Eutrophication occurs when large concentrations of organic matter in bodies of water react with all the available oxygen leaving little or nothing for the fish to breathe.
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Anal Chem 251 Lecture 10 Analysis of Dissolved Oxygen 4 Temperature and Gas Solubility in Water – Thermal Pollution - Review Since dissolved oxygen is crucial for fish, let’s discuss gas solubility. For all gases in water, H solution<0 Solute (g) + water (l) saturated solution (aq) + heat This equation means that gas solubility in water decreases with rising temperature. Solubility of gas in water, mg/L Temperature
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Anal Chem 251 Lecture 10 Analysis of Dissolved Oxygen 5 Temperature and Gas Solubility in Water – Thermal Pollution - Review • Gases have weak intermolecular forces, so there are relatively weak intermolecular forces between a gas and water. • When the temperature rises, the average kinetic energy of the particles in solution increases, allowing the gas particles to easily overcome these weak forces and re-enter the gas phase. • This behavior can lead to an environmental problem known as thermal pollution .
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Anal Chem 251 Lecture 10 Analysis of Dissolved Oxygen 6 Thermal Pollution-Review During many industrial processes, large amounts of water are taken from a nearby river or lake, pumped through the system to cool liquids, gases and equipment, and then returned to the body of water at a higher temperature. A couple of points: 1. The metabolic rates of fish and other aquatic animals increase in the warmer water released near the plant outlet. Thus, their need for oxygen increases but the concentration of dissolved O 2 is lower at the higher temperature. This oxygen depletion can harm these aquatic populations. 2.
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Lecture 11 - Lecture 11 Part 1- Data Synthesis and Cross...

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