Exploring Analytical Data ( PKAS of Citric Acid in Sprite, Rate Law of Crystal Violetreacted with NaOH and Caffeine Extraction from Red Bull) Obtained by Freshman Engineering Students & Researchers at Texas A&M University, Qatar.
The main theme of this paper is to studyphysico-chemical properties in orderto determine the amount of citrate in sprite (a soft drink), the amount of caffeine in Red Bull, and to find the rate law of crystal violet (CV) and sodium hydroxide (NaOH). Theseexperiments were accomplished by undergraduate engineering students during the teaching courses of general and analytical chemistry, CHEM117 and CHEM112 respectively. Several methods were taught to students to obtain the findings of their experimental works. For example, potentiometric titration was conducted in order to determine the ionization constants ofcitric acid, Beer’s law calibration method was used to determine the percentage of caffeine in Red Bull and kinetic studies were carried out to concludethe rate law for the reaction between CV and NaOH atvariable concentrations (Table 2). The findings showed that students were able to work out pKa values of citric acid (2.75, 4.33, 5.63) in sprite. These pKa values which werecomparable to those evaluated by Goldberg et al, were used to deduce aspeciation plot. Frequently, rate order (m=1, n=0)and rate constant (k = 1.55x10-2 S-1, 89%error) of the reaction between crystal violet and NaOH were obtained using the non-linear regression method solver in excel, [CV]/dt = -k[CV]m[NaOH]n.Furthermore, the caffeine extracted from the“Red Bull”(energy drink) was found at 68mg / 250ml, 15% error. The application of the above methods prompts students' thinking toward research and its application on our health and diet system.