Preface
Modern science is not straightforward. Intricate relationships exist among the different disciplines involved in the understanding of virtually every scientific issue and phenomenon. The days of the Renaissance, when a single person could master a large portion of the knowledge then available, are long gone. This is not due to a lack of individual capacity, but rather to the explosion of knowledge, characteristic of our times. Environmental Science and more specifically, Environmental Chemistry...
Experimental Procedure
Estimated time to complete the experiment 2.5 h. 1 1-mL graduated pipet 1 M H2SO4 1 2-mL graduated pipet 8 M NaOH 1 5-mL graduated pipet 50 HNO3 1 spectrophotometer D. I. water 1 - 9 V battery, or a DC converter electrodes (graphite rods, stainless steel and Cu wire) filter paper 1 propipet bulb For these chemical transitions, use a plastic plate with at least six wells (with a minimum capacity of about 3 mL each). If desired, a thin-stem pH probe connected to a pH meter may be used to monitor...
Laboratory Report Sheetexperiment
Measurement of the dissolved oxygen level (D.O.) of an air-saturated sample of D.I. water and a direct sample of tap water Sample A l Air-saturated D.I. water Color of the observed precipitate after the first two reactant additions _ Color of the observed precipitate after the first two reactant additions _ Part B. Dissolved oxygen measurement of an aerated D.I. sample treated with a reducing agent Sample B l Aerated D.I. sample treated with a reducing agent Color of the observed...
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...
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+...
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...
Introduction
Natural aqueous carbonate equilibria play key roles in the characteristics of a water body or a water sample and its buffering capacity. In Nature, such equilibria depend on the solubility constant and therefore on the concentration of Ca2+ and the various carbonate forms. These equilibria will be highly dependent on pH, CO2 concentration in air, CO2 solubility, temperature, and pressure. Carbon dioxide in air dissolves in water, and this process is governed by Henry's constant The carbonate...
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....
