By: Lew Brubacher, University of Waterloo, Waterloo, ON
The Kinetics of a First Order Reaction Chemical Demonstration Kit is a simple display that improves student understanding of reaction order. First-order kinetics come alive as this hydrolysis reaction undergoes repeated color changes.
First-order kinetics come alive as this hydrolysis reaction undergoes repeated color changes of yellow and blue. Bromthymol blue indicator, tert-butyl chloride, water and a known amount of sodium hydroxide are added together forming a blue solution. tert-Butyl chloride reacts with water via hydrolysis to produce acid. When enough acid is produced to neutralize the base, the reaction instantly flashes to yellow—making it easy for students to recognize when a given amount of tert-butyl chloride has reacted. Students time how long it takes to neutralize each batch of base until all the tert-butyl chloride has reacted. Students use these time values to calculate the hydrolysis reaction order. A dramatic and simple demonstration that improves student understanding of the complex idea of reaction order. Teacher Demonstration Notes, along with a reproducible student worksheet and answer sheet are included.
Concepts: First-order kinetics, hydrolysis, indicators. Time Required: 15 minutes
Correlation to Next Generation Science Standards (NGSS)
Science & Engineering Practices
Analyzing and interpreting data Using mathematics and computational thinking Constructing explanations and designing solutions
Disciplinary Core Ideas
MS-PS1.B: Chemical Reactions HS-PS1.B: Chemical Reactions
Crosscutting Concepts
Cause and effect
Performance Expectations
MS-PS1-1: Develop models to describe the atomic composition of simple molecules and extended structures.
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