In the Equilibrium Constant Chemistry Laboratory Kit, students use colorimetry to find the equilibrium constant for a reversible chemical reaction. The equilibrium constant is simply the constant for a reaction at equilibrium.
The more a reaction at equilibrium changes, the more it stays the same! That’s because the only “constant” for a reaction at equilibrium is a mathematical relationship of concentrations called the equilibrium constant. In this quantitative experiment, students use colorimetry to determine the equilibrium constant for a reversible chemical reaction. Students first measure the absorbance of a reference solution containing a known concentration of the product. They then prepare solutions having different starting concentrations of reactants and allow the solutions to come to equilibrium. The equilibrium concentration of the product in each solution is determined by comparing its absorbance to that of the reference solution. The equilibrium constant for the reaction can then be calculated using stoichiometry and the balanced chemical equation. Includes all the chemicals and pipets needed for the experiment, along with reproducible student handouts, detailed background information and complete Teacher Notes with sample data and answers to all questions.
Complete for 30 students working in pairs.
Correlation to Next Generation Science Standards (NGSS)
Science & Engineering Practices
Analyzing and interpreting data Using mathematics and computational thinking
Disciplinary Core Ideas
MS-PS1.B: Chemical Reactions HS-PS1.B: Chemical Reactions