Flame Tests Chemistry Lab for High School | Flame Test Experiment Guide

Flame tests are a classic high school chemistry lab that allow students to identify metal ions based on characteristic flame colors. In this flame test chemistry lab, students observe how different elements emit distinct colors when heated, helping them connect atomic structure, electron energy levels, and atomic emission to real laboratory observations. This flame test experiment is easy to set up, highly visual, and consistently engaging for high school chemistry students, making it an ideal lab for teaching electron configurations, periodic trends, and the behavior of excited electrons.

This flame test lab is an absolute favorite of mine and a much loved lab by all of my students. The best time to use this lab is when teaching atomic structure, electron configurations, energy levels, ground state, and excited state.  

TLDR? Go straight to my TPT store to view this flame test lab.

📌 What is the Purpose of a Flame Test?

A flame test is used to detect the presence of certain metal ions. The test involves heating a sample of the element and observing the resulting color of the flame. When atoms of elements are heated to high temperatures, some electrons may absorb enough energy to allow them to move to higher energy levels. The element is then said to be in the "excited state." This excited atom is unstable, and the electrons quickly return back to their positions of lower energy or their ground state. As the electrons return to their ground state, the energy that was absorbed is given off in the form of visible light. The color of this light can be used to identify the elements involved. In a flame test, the element will give off a characteristic color that serves as a simple method of identification of that element.   

📌 Purpose

• To observe the characteristic colors produced by metallic ions when heated in a flame.
• To identify an unknown metallic ion by means of its flame test.
• To identify the components of a mixture using cobalt glass.

📌 Required Materials

Bunsen burner, Lab apron, Wood Splints, Safety goggles, Unknown solutions, Test Tubes, Cobalt glass squares, Test Tube Racks, Nitrate solutions of sodium, potassium, lithium, calcium, strontium, barium, and copper.

📌 Step by Step Procedure, Tips, and Suggestions

• I like to set up different lab stations and have the students rotate through the stations. I set up stations for the 7 different metal ions that I will have the students test. Students are required to rotate through these 7 stations first. The standard flame test procedure helps students identify metal ions based on characteristic flame colors.
• After the students have identified the colors of the above 7 metal ions, I assign an unknown for them to identify.  
• Finally, I have the students use cobalt glass to identify the components of a mixture.

• I have used metal inoculating loops as a means of heating the metal ion sample, but I prefer to use wood splints. They are cheap and disposable. Be sure to soak them in the metal nitrate solutions prior to the start of the lab. 

I set up individual lab stations for each metal ion and have students rotate through the stations. 

In a flame test, the element will give off a characteristic color.  It is difficult to catch on camera, but the photos in this post show the characteristic colors of barium (lime green) and lithium (crimson).

 

After students have observed all colors, I assign them an unknown element to identify. 

Using cobalt glass, students determine the identity of elements in a mixture. 
When viewing the flame test with the naked eye, the student will see the yellow color of sodium.
When viewing the flame test while looking through the cobalt glass the student will see the violet color of potassium.

To me this lab serves a greater purpose than just learning to identify metal ions from their flame tests. This lab gets my students so excited about chemistry.... and that excitement makes all the difference in the world when trying to teach chemistry to high school students.

Flame Test Lab FAQs

What is the purpose of the flame test lab?
The purpose of the flame test lab is to help students identify metal ions based on the characteristic colors they produce when heated in a flame. This lab reinforces the concept of electron excitation and emission while giving students hands-on experience with atomic structure and spectroscopy concepts commonly taught in high school chemistry.

Why is cobalt glass used in a flame test?
Cobalt glass is used in a flame test to filter out the intense yellow light produced by sodium ions. Because sodium is commonly present as a contaminant, its bright emission can mask other flame colors. Looking through cobalt glass helps students more clearly observe the true flame colors of other metal ions.

This lab is in my TpT store and can be viewed at this link.

Have Fun Teaching!