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 of the Lab:

• 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 Procedures, 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!

Chemistry Lab: How Big Is A Mole?

Two facts we all know about teaching chemistry:

• The concept of a "mole" is absolutely crucial to the teaching of our class.
• Many of our students struggle with this concept every single year.

According to the textbook:  A mole is the quantity of a substance that has a mass in grams equal to its molecular mass and contains Avogadro's number of particles.   I think that many students memorize the definition of a mole, but fail to grasp the concept of a mole.  I want my students to be able to visualize a mole and to have a grasp on the size of a mole of substance.

I just added a new lab to my yearly chemistry curriculum.  It is not really an "experiment" but more of a review and reinforcement of the mole concept. The idea of the activity is very simple:  Students are given ordinary household substances and are asked to determine how many moles are in a teaspoon of the substance.

Purpose: 

1. To determine the number of molecules and/or atoms in small amounts of everyday substances.
2. To determine how many moles of chalk it takes to write your name on the board.

Materials:               

• Balance           
• Weighing dishes        
• Plastic spoons
• Water              
• Salt (NaCl)                 
• Sugar (C₁₂H₂₂O₁₁₎
• Chalk              
• Chalkboard    

I had the students find the mass of a teaspoon of a substance.  From this mass, I had students determine the number of moles of substance, the numbers of molecules of substance, and the number of a particular atom within the substance.  The bottom line is that this activity provides repetitive practice in mole conversions.

I was a little concerned that my "sophisticated" high schoolers would find this activity too elementary.  Wrong!!  They embraced the activity whole-heartedly and came away with a better understanding of the "size" of a mole.

The activity concludes with a student-designed experiment.  I asked my students to design an experiment to determine the number of moles of chalk required to write their name on the chalkboard.  Students had to write the steps of their procedure, construct a data table, and convert their data to moles and molecules.  SO SIMPLE, but my students had a great time with this.  They enjoyed comparing the "size" of their name to that of their classmates.

Click above picture to view this product in my TpT store.

Informational Text Reading with Graphic Organizers

Here's a great new free item for your science classroom:  

DNA Informational Text Reading with Graphic Organizers

I teach in a Common Core state, and in a school that is really pushing the implementation of the Common Core State Standards.  We have to show evidence of this implementation in our classroom.  I obviously have to do what is required of me by my admin, but at the same time, I do not want to lose valuable classroom teaching time and get behind on the vast amount of course content that I am also required to teach.

I recently developed this lesson for my students.  In our unit on DNA, RNA, and Protein Synthesis, I love to tell the history of Watson and Crick and their discovery of the structure of the DNA molecule.  In 1953, James Watson and Francis Crick rocked the scientific world with their discovery, and with the publication of their one-page paper in Science magazine describing the DNA molecule.  This one-page paper is a marvelous bit of history, and it is a fascinating read.  It is also a perfect piece of informational text that can be used to teach the Common Core State Standards.

The one-page article can be printed and used in your science classroom.  I developed a 4-page set of graphic organizers to go along with this article.  As students read the article they are required to complete the graphic organizers. You can have your students complete all four organizers (I usually do!) or each graphic organizer can be used alone. The printable lesson is perfect for traditional classroom settings, and the paperless, digital Google Apps version is perfect for distance learning and 1:1 classrooms.

You can, of course, use class time for this activity, but I usually assign this as a homework assignment.  I assign this at the beginning of my unit on DNA, and usually give a week to complete the assignment. The article and the graphic organizers provide great review on the topics I am teaching in class, as well as a lesson in the reading of informational text.  It's a win-win!  (Pssst...This is also a great activity to leave in your sub folder in the event of your unexpected absence from school!)

Here is a look at each of the graphic organizers:

(They look best if printed in color, but print perfectly fine in grayscale.)

This is a free download, and will always remain a free download.  Enjoy!

Related products include:

DNA, RNA, and Protein Synthesis Complete Unit Plan Bundle

Genetics Complete Unit Plan Bundle

FREE DNA Extraction Lab

Chemistry Lab: Composition of a Hydrate

This is one of my favorite chemistry labs and here's why: It has a simple materials list. It is easy to set up and break down. It yields great results. It provides a quality lab during your unit on chemical formulas, a unit in which labs are hard to come by. It has a mathematical component which students need. Students calculate percent error. Students learn how to write the formula of a hydrate. Students compare experimental data to theoretical data, which is so important!

That's a lot of reasons why you should do this lab! 

Here is the link in my TPT store:  Composition of Hydrates Lab

It's best to use this lab when teaching your unit on how to write chemical formulas and how to name chemical compounds. Hydrates are compounds that have some number of water molecules attached to them. The premise of the lab is simple: A known mass of a hydrate is heated to release the water of hydration. The mass of the resulting anhydrous salt is determined. The difference in the mass of the hydrate and the mass of the anhydrous salt can be used to determine the formula of the compound.

In our lab, we used copper (II) sulfate pentahydrate. A fine crystal is needed for the lab. Since we only had the medium crystal in stock, my students used a mortar and pestle to grind the crystals into a finer powder.

The hydrate is heated over a Bunsen burner in an evaporating dish to remove the water of hydration. But first the empty evaporating dish must be heated to remove all water, allowed to cool briefly, and the mass of the empty dish determined. 

The difference in the "before mass" and the "after mass" is used to determine the mass of water lost. Students are given directions in how to use this information to determine that the compound used was copper (II) sulfate pentahydrate. 

I love the simplicity of this lab and the fact that my students clearly understood how to use this data to determine the formula of the compound. All in all, it's a great day in the lab!

How much Vitamin C is in your fruit juice?

Lab: Determining the Amount of Vitamin C in Fruit Juices

I  have been doing this lab every year for a long, long time.  I always enjoy it, and so do my students. I often do this lab with my biology students when teaching about nutrition and digestion, but my favorite use of this lab is with my chemistry classes.  This lab is perfect to introduce the idea of titrations, equivalents, and as a review of dimensional analysis.

In this experiment the student will use a lab procedure known as a titration to determine the amount of Vitamin C found in a 6 ounce serving of various fruit juices.  I most often use orange juice, pineapple juice, and apple juice. 

A titration is the controlled addition and measurement of the amount of a solution of known concentration required to react completely with a measured amount of a solution of unknown concentration.  Titration provides a means of determining the chemically equivalent amounts of two substances.  

The materials list is short and consists of items found in almost all labs..... no fancy equipment required!  You will need:  Spot plate, Thin stemmed or microtip Beral pipets  (or medicine droppers),  White paper for background, Ascorbic acid standard solution,  Apple juice,  Orange juice,  Pineapple juice, Starch solution,  Iodine solution and Plastic Toothpick (stirrer).

In order to determine the amount of Vitamin C in the fruit juice, the student must first do a titration using a vitamin C (ascorbic acid) solution of known concentration.  An iodine/starch complex is used so that a color change can be detected.  The number of drops of iodine added will be used to determine the amount of Vitamin C present in the juice.  

When ascorbic acid (Vitamin C) comes into contact with iodine, it is oxidized to form dehydroascorbic acid.  When Vitamin C and iodine are in solution together, they will form iodide.  As iodine is added during the titration, iodide will continue to be formed until there is no more Vitamin C left in the solution.  At this point, iodine becomes present in the solution and the starch turns a blue-black color.  The starch is used as an indicator because it turns black in the presence of iodine, but not for iodide.  The amount of iodine that is added during the titration can be used to indicate the amount of Vitamin C present in the fruit juice.

Set up for the lab is quick and easy, and does not take a lot of advance preparation.  

This lab is available in my TpT store and can be viewed here:  Determining the Amount of Vitamin C in Fruit Juices.