Cart
Article
An Experiment in the Sampling of Solids for Chemical Analysis
Hi-Res PDFPurchase the full-text
- PDF/HTML,
figures/images,
references and tables,
(where available)
Abstract
An experiment is described that is suitable for demonstrating the principles of sampling uncertainty in the chemical analysis of particulate materials. Although uncertainty due to the sampling of heterogeneous materials is a pervasive problem in the analysis of "real world" samples, there are very few experiments designed to introduce this topic into the undergraduate laboratory. In the experiment described here, students analyze mixtures of KH2PO4 and NaCl (0.5 to 0.8% KH2PO4), with sample masses between 0.1 and 2.5 g, and observe the effect of sample size on analytical uncertainty. The variance due to sampling is isolated from other sources of variance and used to estimate Ingamells' sampling constant, Ks, for the mixture. The determination of phosphate is performed using the molybdenum-blue method implemented on a simple flow-injection apparatus, which permits a high sample throughput. The experiment is easily completed by two students in one laboratory period and consistently shows improved analytical precision with increasing sample size. Values for Ks typically range from 100 to 1000 g.
Keywords (Audience):
Second-Year UndergraduateKeywords (Domain):
Laboratory InstructionKeywords (Pedagogy):
Hands-On Learning / ManipulativesKeywords (Subject):
Laboratory Equipment / ApparatusCiting Articles
Citation data is made available by participants in CrossRef's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search in SciFinder.
This article has been cited by 6 ACS Journal articles (5 most recent appear below).
A Laboratory Exercise To Demonstrate the Theory and Practice of Analytical Sampling
Brian A. Logue and Stephanie L. YousoJournal of Chemical Education2010 87 (3), 316-319A Laboratory Exercise To Demonstrate the Theory and Practice of Analytical Sampling
Brian A. Logue and Stephanie L. YousoJournal of Chemical Education2010 87 (3), 316-319In analytical chemistry classes, the importance of gathering a proper sample for analysis of bulk materials is often addressed only briefly or not at all. Although a number of classroom and laboratory exercises have been developed to illustrate factors ...
Analysis of Iron in Lawn Fertilizer: A Sampling Study
Michael A. JeannotJournal of Chemical Education2006 83 (2), 243Analysis of Iron in Lawn Fertilizer: A Sampling Study
Michael A. JeannotJournal of Chemical Education2006 83 (2), 243A novel laboratory activity in sampling statistics, suitable for students in a quantitative analysis course, is described. In this activity, students measure the percentage of iron in a commercial lawn fertilizer by simple sorting and weighing. The pooled ...
A Demonstration of Sample Segregation
Mark D. Fritz , Stephen B. Brumbach , JudithAnn R. HartmanJournal of Chemical Education2005 82 (2), 255A Demonstration of Sample Segregation
Mark D. Fritz , Stephen B. Brumbach , JudithAnn R. HartmanJournal of Chemical Education2005 82 (2), 255Handling a solid mixture can segregate its particles by size. A simple, visually-compelling demonstration shows students how stirring or pouring can segregate a mixture and create a nonuniform sample. The demonstration uses colored beads and other ...
Two Experiments Illustrating the Importance of Sampling in a Quantitative Chemical Analysis
David HarveyJournal of Chemical Education2002 79 (3), 360Two Experiments Illustrating the Importance of Sampling in a Quantitative Chemical Analysis
David HarveyJournal of Chemical Education2002 79 (3), 360With many instructors of quantitative analysis courses emphasizing the analysis of "real-world" samples, there is a need for more experiments illustrating the importance of sampling as a source of uncertainty. Unfortunately, the few available experiments ...
Recovery and Reutilization of Waste Matter from Coffee Preparation. An Experiment for Environmental Science Courses
Santino OrecchioJournal of Chemical Education2001 78 (12), 1669Recovery and Reutilization of Waste Matter from Coffee Preparation. An Experiment for Environmental Science Courses
Santino OrecchioJournal of Chemical Education2001 78 (12), 1669This work is designed as an experience for organic and analytical chemistry laboratories in environmental science courses. Coffee grounds were chosen because they are easily available, they are a fine example of a waste product, and the students are ...
Full Text HTMLTools
-
Add to Favorites
-
Download Citation
-
Email a Colleague -
Permalink
Order Reprints
Rights & Permissions
Citation Alerts
History
- Received: August 03, 2009
ACS
Network
Facebook
Tweet This
CiteULike
Newsvine
Digg This
Delicious
