Hydrogen peroxide, H₂O₂, is notoriously unstable and light sensitive, and therefore it is difficult to maintain a solution of H₂O₂ at a specified concentration. Commercial hydrogen peroxide is packaged in an opaque bottle, usually a brown color, to shield the H₂O₂ molecules from light. The concentration of commercial hydrogen peroxide is usually 3% (w/v).

Over-the-counter pain medications can be tricky to formulate into tablets because there are contradictory goals. First, the tablets should not chip or break apart when stored in a bottle with other tablets. Second, the tablets should fall apart easily when a person chews or swallows them.

In the scenario for this investigation, you are a formulations chemist working for a pharmaceutical company. Your company has received numerous complaints about one of your products—a pain medication tablet that is a simple combination of acetaminophen and sucrose. The sucrose is added as a binder. Customers have opened bottles of the product to find most of the tablets chipped and cracked. The team in charge of production has presented your group with two theories for the chipping problem.

• The tablet formula, which should be 85% acetaminophen and 15% sucrose, by mass, is incorrect. This makes the binding properties weak and therefore parts of the tablet chip off when struck by other tablets in a bottle.
• The acetaminophen has been contaminated with a small amount of aspirin, and the aspirin is causing the tablets to chip and crack.

There are many different brands of beverages that fall under the general category of “sports drinks.” Most of these beverages contain an FD&C food dye to color the beverage. There are a few options available to determine how much food dye is contained in a sports drink. A common, and very accurate, test method involves using an instrument called a spectrophotometer.

In brief, a spectrophotometer projects light through a small sample of a colored solution. The molecules in the solution allow some, but not all, of the wavelengths of light to pass through the sample and reach the spectrophotometer’s detector. By carefully analyzing what happens to light as it passes through a sample of liquid, a great deal can be learned about some of the molecules in the liquid.