Temperature and the Rate of Chemical Reactions

Purpose

The purpose of this lab is for students to investigate the effect of temperature on the rate of a chemical reaction.

Key Science Topics

  • Kinetic Molecular Theory of Heat
  • Energy transformation (e.g., chemical energy to light {or radiant} energy)
  • Electron energy levels, absorption and emission
  • Fluorescence

Grade Level

  • Physical Science, Grades 6-9

Student Prior Knowledge

  • Students should be able to define the Kinetic Molecular Theory of Heat.
  • Students should be familiar with the Bohr model of the atom and electron energy levels.
  • While it would be helpful if students were familiar with electron energy levels and absorption/emission of photons, this activity could be used to introduce that concept.

Materials

Each lab group should have the following:

  • Three beakers labeled A, B, and C
  • Thermometer
  • Three glow sticks that are the same size, brand, and color
  • Hot, room temperature, and cold water

I have used mini glow sticks up to the regular-sized glow sticks. Be sure to have extra on hand as some glow sticks will not react. After Halloween is a good time to stock up on glow sticks at a bargain price. Science supply stores (especially on-line) and party stores are good sources as well.

This may also be done as a teacher demo and have students record the data.

Resources

Suggestions

I usually use this lab as an introduction to atomic spectra—a challenging topic for middle school, high school and college students. This lab is a good review of how the Bohr model; while it is an incomplete description of the atom, is a good model for explaining electron energy levels.

To explain electron energy levels, I use the standard climbing on a chair, then a lab table method. While standing on the ground, I explain that I am on the ground state. If I absorb just the right amount of energy, I will then have enough energy to hop up onto the chair. I then stand on the chair and ask my students if that required energy. Yes. Then I describe that if I absorb yet another packet of energy, I can move up to the second level. Or, I can hop down to the ground state and give off energy. If I hop down to the ground state, I emit a packet of energy which is a photon, or particle of light. I also mention that I can [theoretically, at least] go from the ground state directly up to the table (2nd level). I can also jump directly from the table to the ground state and bypass the first state entirely [theoretically speaking again].

Further Reading

For further information on how glow sticks work, please visit the following sites:

Common Core Standards

Next Generation Science Standards

Published: 01 October, 2015

Fun Fact

A day on Venus lasts longer than a year - Venus takes takes 243 Earth days to spin once, but only 224.7 Earth days to go round the Sun.