Versatile Three-in-One Single Beam Visible Colorimeter for Undergraduate Chemistry Laboratories

Abstract

In this work, we have developed a versatile three-in-one single beam visible colorimeter for undergraduate laboratory courses. The battery and mains electricity supply (utility power), wired and wireless data logging, and 3D-printed components are three important highlights of the developed visible colorimeter. The system is based on a low-cost ARDUINO UNO microcontroller and can measure the absorbance of the liquid samples in the visible region of the electromagnetic spectrum. For on-field measurements, the present colorimeter can work on a small 9 V battery. Therefore, the present portable colorimeter can be used for different field studies. In addition to this, the system can also work on a mains electricity supply for benchtop measurements. The measurement results can be displayed on an OLED display or can be recorded using an open-source data acquisition tool on personal computers/laptops. In addition to this, measured data can be transmitted using a Bluetooth module to Android phones. For this, an open-source Android application was developed using the MIT App Inventor web application. For rapid prototyping of the system, all components of the visible colorimeter are designed and developed using 3D-printing technology. The functioning of the colorimeter was tested by measuring the absorbance of aqueous KMnO4 and K2Cr2O7 samples, and experimental results were compared with the commercially available single beam visible colorimeter. The measurement difference between the present colorimeter and commercial spectrophotometer was less than 4%, suggesting the satisfactory performance of the colorimeter. Therefore, students can use the present system to understand some basic concepts of the colorimeter.