Prev. Article Next Article Table of Contents

Article

A Low-Cost Device for Automatic Photometric Titrations

Citing Articles

Your current credentials do not allow retrieval of the full text.

Purchase the full-text

PDF/HTML,
figures/images,
references and tables,
(where available)

Fábio R. P. Rocha

Departamento de Quí, Universidade Federal de São Carlos, São Carlos, Brazil

Boaventura F. Reis

Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, PO Box 96, 13400-970 Piracicaba, SP, Brazil

J. Chem. Educ., 2000, 77 (2), p 258

DOI: 10.1021/ed077p258

Publication Date (Web): February 1, 2000

Section:

History, Education, and Documentation

Abstract

Electronics is an important topic in chemistry courses. However, the introduction of basic concepts is often difficult and the lab instruments are frequently seen as "black boxes". To address this problem, we propose the construction of a simple, low-cost (about $150 U.S.) automatic photometric titrator employing a light-emitting diode (LED) and a phototransistor. The electronic circuit can be assembled by the students themselves. The device was employed to implement a common procedure in chemical labs, making feasible the introduction of concepts related to electronics in undergraduate chemistry courses. The titrator is able to work automatically, since a feedback system permits stopping the addition of titrant solution when the end-point is achieved. With this demonstration, it can be stressed that automatic procedures can be implemented without expensive instruments. Additionally, a classical procedure becomes more attractive to the students and its importance to chemical analysis can be emphasized. The feasibility of the titrator was demonstrated by acid-base titrations of HCl solutions with NaOH in the presence of phenolphthalein and by iodimetric determination of ascorbic acid in vitamin C tablets and lemon juice. Precise results (0.7% relative standard deviation, n = 10) in agreement at the 95% confidence level with those attained by a conventional procedure were obtained.

Keywords (Audience):

Second-Year Undergraduate

Keywords (Domain):

Analytical Chemistry

Keywords (Subject):

Instrumental Methods

View: Hi-Res PDF | PDF w/ Links

Citing 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 1 ACS Journal articles (1 most recent appear below).

Applied Electronics: Construction of a Simple Spectrophotometer
Melissa A. Thal , Michael J. Samide
Journal of Chemical Education2001 78 (11), 1510
- Applied Electronics: Construction of a Simple Spectrophotometer
  Melissa A. Thal , Michael J. Samide
  Journal of Chemical Education2001 78 (11), 1510
  In this paper we describe the construction of a simple spectrophotometer intended for use as a capstone circuit for an electronics laboratory exercise. Students in the undergraduate laboratory have learned basic circuitry and are now able to read a ...
  Abstract | Hi-Res PDF | PDF w/ Links