Prelaboratory Report Sheetexperiment

Explain why the dissolved oxygen content of an environmental sample of water is important. 2. Look up the reported limit values for dissolved oxygen in water so that a system may support aquatic life. What would be the limit value for a system to still be considered aerobic Anaerobic 3. Explain what contributes or favors an increased value of dissolved oxygen in water. 4. Which are the main types of pollutants that affect the level of dissolved oxygen in water 5. In what cases would it be...

Introduction

In response to the expanding stresses on the environment and in the belief that there is no single criterion by which to adequately judge the potential hazard of a given substance (either to the environment or to humans), several biological assay procedures have been developed, proposed, and used to assay toxicant impacts. In general, there are two main groups of in vitro toxicity-screening tests (a) the health effect tests, and (b) the ecological effect tests. Health effect toxicity tests are...

Dissolved Oxygen in Water

After performing this experiment, the student shall Determine the level of dissolved oxygen in a sample of water using Winkler's method. Analyze the effects of various factors on the level of dissolved oxygen in a water sample (e.g., salt content, temperature, degree of mixing, and the presence of reducing compounds). The level of dissolved oxygen in water is one of the most important parameters in determining its quality, because it indirectly indicates whether there is some kind of pollution....

Postlaboratory Problems And Questions

The surface-ionization models (or surface-complexation models) account for the behavior of solid oxide suspensions, which usually behave as amphoteric substances. The most common are given in Table 1 (see Bourikas, 2005 Blesa, 1997 Davranche, 2003). Table 1. Surface-ionization models (8 and e are fractional charges). Name Surface ionization model constants One site onepKa M - OH8+ < * M 0< 1_8)_- - H+ Ka -M - OHj < i M - OH + H+ Kal -M OH < i M O- + H+ Ka2 -Vi - OH2s+ M-OH(1-S)-+ H+...

Experimental Procedure

Estimated time to complete the experiment 2 h (either the instrumental or the non-instrumental options). 6 3-mL screw-capped conical bottom vials with rubber septa 2 2-mL microburets 2 Beral pipets 1 test tube (5 mm I.D., 5 cm tall) 1 UV-lamp Ba(OH)2 Ca(OH)2 0.02 M H2SO4 0.003 rhodamine-B D. I. water FeS04-7H20 30 H202 MnCl2 4H20 With the seven glass capillary tubes make U-shaped capillaries with the aid of a flame from a match or a cigarette lighter (alternatively, plastic capillary tubing may...

Student Comments and Suggestions

Sulfur can be recovered from gypsum in the form of elemental S and H2SO4 through the following (simplified) reaction sequence (see Campbell, 1971) CaS04 is heated in the presence of a mixture of reducing gases (i.e., H2 and CO) to produce five binary compounds U + V + W + X + AY for every two moles of CaS04. The last four binary compounds produced are oxides (basic, acidic, acidic, and amphoteric, respectively). U reacts with W and Y to produce H2S + T. Reaction c Heating T produces V + W....

Alkalinity and Buffering Capacity of Water

After performing this experiment, the student shall Determine the alkalinity and buffering capacity of several types of water samples surface water, groundwater (mineral water) and sea water. Prepare different solutions or mixtures of acids and their conjugate bases (i.e., buffers), and measure their buffering capacity by titration with acids and bases. Calculate the concentrations of an acid and of its conjugate base to create a buffer for a desired buffering capacity at a specific pH. This...

Prelaboratory Questions And Problems

Knowing that Zn(II) hydroxide is amphoteric and that it forms divalent ions in acidic and in basic solutions, a) Replace the alphabet letters in the boxes in Figure 2 with the chemical formulas of the missing species. b) Write the (balanced) equations that describe each one of the equilibrium lines in this diagram (except the dotted ones, that represent the water equilibria these two lines do not participate directly in the Zn equilibria). c) Justify chemically and or algebraically the type...

Literature References

ERCO Worldwide, http clo2.com index.html Esposito, A.P. Stedl, T. Jonsson, H. Reid, P. J. Peterson, K. A. Absorption and Resonance Raman Study of the 2B (X) 2A2(A) Transition ofChlorine Dioxide in the Gas Phase, J. Phys. Chem. A, 1999,103, 1748-1757. Green, T. J. Islam, M. Canosa-Mas, C. Marston, G. Wayne, R. P. Higher Oxides of Chlorine Absorption Cross-sections of CI2O6 and CI2O4, the Decomposition of C1206, and the Reactions of OCIO with O and 03, J. Photochem. Photobiol. A Chemistry 2004,...

Water Characterization

After performing this experiment, the student shall be able to Measure several parameters that indicate the characteristics and differences of various types of natural water samples surface water, groundwater mineral water and seawater. The parameters to be explored in this experiment will help us determine the main differences among water samples. They include pH, conductivity, chloride and sulfate concentration, and hardness level as measured by the total amount of calcium and magnesium ions...

Analytical Environmental Chemistry Experiments in the Literature

A New Project-Based Lab for Undergraduate Environmental and Analytical Chemistry, J. Chem. Educ. 2006, 83, 253-256. Anderson, C. P. Saner, W. B. A Practical Experiment for Determining a Pervasive, Persistent Pollutant, . Chem. Educ. 1984, 61, 738739. Allen, H. C. Brauers, T. Finlayson-Pitts, B. J. Illustration of Deviations in the Beer-Lambert Law in an Instrumental Analysis Laboratory Measuring Atmospheric Pollutants by Differential Optical Absorption Spectrometry, J. Chem. Educ....