Premium Essay

Dissolved Oxygen Using Winkler's Method

In:

Submitted By naveeky
Words 3465
Pages 14
12.097 Environmental Chemistry of Boston Harbor – IAP 2006

Lab 1:
DETERMINATION OF DISSOLVED OXYGEN BY WINKLER TITRATION
1. Background
Knowledge of the dissolved oxygen (O2) concentration in seawater is often necessary in environmental and marine science. It may be used by physical oceanographers to study water masses in the ocean. It provides the marine biologist with a means of measuring primary production - particularly in laboratory cultures. For the marine chemist, it provides a measure of the redox potential of the water column.
The concentration of dissolved oxygen can be readily, and accurately, measured by the method originally developed by Winkler in 1888 (Ber. Deutsch Chem. Gos., 21, 2843).
Dissolved oxygen can also be determined with precision using oxygen sensitive electrodes; such electrodes require frequent standardization with waters containing known concentrations of oxygen. They are particularly useful in polluted waters where oxygen concentrations may be quite high. In addition, their sensitivity can be exploited in environments with rapidly-changing oxygen concentrations. However, electrodes are less reliable when oxygen concentrations are very low. For these reasons, the Winkler titration is often employed for accurate determination of oxygen concentrations in aqueous samples.
2. Scope and field of application
This procedure describes a method for the determination of dissolved oxygen in aqueous samples, expressed as mL O2 (L water) -1. The method is suitable for the assay of oceanic levels of oxygen in uncontaminated seawater and is based on the
Carpenter (1965) modification of the traditional Winkler titration.
3. Definition
The dissolved oxygen concentration of seawater is defined as the number of milliliters of dioxygen gas (O2 ) per liter of seawater (mL L -1 ).
4. Principle of Analysis
The chemical

Similar Documents

Premium Essay

Feretetetrt

...World Bank & Government of The Netherlands funded Training module # WQ - 11 The chemistry of dissolved oxygen measurement New Delhi, May 1999 CSMRS Building, 4th Floor, Olof Palme Marg, Hauz Khas, New Delhi – 11 00 16 India Tel: 68 61 681 / 84 Fax: (+ 91 11) 68 61 685 E-Mail: dhvdelft@del2.vsnl.net.in DHV Consultants BV & DELFT HYDRAULICS with HALCROW, TAHAL, CES, ORG & JPS Table of contents 1 2 3 4 5 6 7 8 Module context Module profile Session plan Overhead/flipchart master Evaluation sheets Handout Additional handout Main text 2 3 4 5 29 31 38 39 HP Training Module File: “ 11 Chemistry of DO measurement.doc” Version 05/11/02 Page 1 1 Module context This module deals with significance and chemistry of dissolved oxygen measurement. Modules in which prior training is required to complete this module successfully and other available, related modules in this category are listed in the table below. While designing a training course, the relationship between this module and the others, would be maintained by keeping them close together in the syllabus and place them in a logical sequence. The actual selection of the topics and the depth of training would, of course, depend on the training needs of the participants, i.e. their knowledge level and skills performance upon the start of the course. No. 1 Module title Basic water quality concepts Basic chemistry concepts Code WQ - 01 • • • • • 3 How to prepare standard solutions WQ - 04 • • • 2 WQ - 02 ...

Words: 4977 - Pages: 20

Free Essay

Boom

...Full Length Research paper Effects of feeding frequency on growth, feed efficiency and economic viability of rearing African catfish (Clarias gariepinus, Burchell 1822) fingerlings and juveniles A. Z. Aderolu*, B. M. Seriki, A. L. Apatira and C. U. Ajaegbo Aquaculture Nutrition Unit, Department of Marine Sciences, University of Lagos, Akoka-Lagos, Lagos State, Nigeria. Accepted 16 December, 2009 Feeding frequency effect on growth performance, feed utilization and economic viability of Clarias gariepinus fingerlings and juveniles were studied under natural photoperiods of 12/12 h light/dark cycle using a complete random design. Triplicate group of 10 fish with an initial mean weight of 8.5 ± 0.1 g and 34.3 ± 0.1 g respectively per tank (measuring 52 x 33.5 x 21 cm). A commercial feed (COPPENS) with crude protein of 42% and ether extract 12% was fed for 8 weeks over four feeding frequencies studied (once, twice, thrice and four times). Mean weight gain, relative growth rate and the specific growth rate were all significantly different (P < 0.05) across feeding levels except at thrice and four times feeding levels. The feed conversion ratio was lowest on three times a day feeding level both for the juvenile and fingerling (0.66 and 0.73, respectively). Although net profit value, in both juvenile and fingerling group are not significantly different, the investment cost analysis and the gross profit between fish fed thrice and four times are equally not significantly...

Words: 2845 - Pages: 12