General Chemistry 115b

Lab 8: The Cola Project - An Analysis of the Phosphorus Content of Cola

Jeffrey Doan

Arushi Gulati, Megha Gupta, Andrew Friedman

March 31, 2015

Abstract

A staple of many a 21st century diet is the highly acidic, drink cola. The acidity can be partially attributed to a concentration of phosphoric acid dissolved as a flavoring additive. The purpose of this experiment was to examine and analyze a sample of Coca-Cola to determine the phosphoric acid concentration and the ppm of phosphorus in cola through both a titrimetric and a spectrophotometric approach. Ultimately, it was determined via an average of the two methods that there is 162.5 ppm phosphorus in cola, with a percent error between the two methods of 8%. Upon considering an official document published by the Coca-Cola Company, however, which showed the actual concentration of phosphorus to be 172 ppm (“What is in Coca-Cola?: A Briefing on Our Ingredients,” 2011), it is clear that the more accurate of the two methods used is the titrimetric method of analysis.

Introduction

Phosphorus, often found in inorganic phosphate groups, serves a variety of functions within the human body. Firstly, 85% of phosphorus found in the body is used in skeletal development, where it functions in bone mineralization (“Food Phosphate: Questions and Answers”, 2007). Inorganic phosphate (Pi) also plays a critical role in mineral metabolism and other cellular functions such as energy transfer mechanisms and creating phosphorylated intermediates in cellular signaling (Takeda et al., 2004). Furthermore, it is a major component of important molecules such as phospholipids, which make up the phospholipid bilayer in cellular and organelle membranes, and the phosphate groups in DNA and RNA nucleotides (Takeda et al., 2004). Lastly, inorganic phosphate groups also make up myelin and collagen in ligaments and tendons (“Food Phosphate: Questions and Answers,” 2007).

The concentration of inorganic phosphate is carefully...