This article is explaining two lab activities, first one is to prepare solutions and second is for making dilutions. We can understand the solutions by their solute concentration, a measure of how much solute is present per unit of solution. A concentrated solution is called a “stock solution” and the diluted solution is called the “working solution”. The objective of this article is to prepare a solution, and measure the absorbance of working solutions at various concentrations using a spectrophotometer.