Flame Test Experiment

Hello again! This is my third blog of the year and I definitely think I am getting the hang of it. If you look back at the last two, you could call them complete disasters. This time I plan on being AWESOME! As you can see in the title, this blog is about the flame test experiment that my teacher, Ms. Janik, demonstrated to the class. We observed how different compounds can affect the color of a flame.  

Purpose: To Demonstrate and classify the characteristics of a chemical reaction.

Objective: Describe the difference between a physical and chemical change.

We tested seven different compounds, plus a mystery substance that was kind of a surprise at the end.

Here is the data table that shows the chemical compounds we used, the elements involved, and the characteristics of the flame when the compound mixed within it.

Chemical Compounds:	Elements Involved:	Characteristics:
Barium Chloride	BaCl	Light Green
Calcium Chloride	Ca Cl	Orange
Lithium Chloride	LiCl	Dark Pink
Potassium Chloride	K Cl	Blue
Sodium Chloride	Na Cl	Dark Yellow
Strontium Chloride	Sr Cl	Red
Aluminum Foil	Al	Bright Yellow Sparks
Mystery Substance	BaCl and Li Cl	Barium Chloride Lithium Chloride

Analysis Questions:

1.) What indicators (at least 3) determine that a chemical change (or reaction) has occurred?

A chemical reaction has taken place when:

Energy is absorbed or given off in a reaction, there is a change in color, there is a change in odor, a liquid produces a gas or a solid, or chemical changes are irreversible and new substances are made.

2.) What is emitted when a chemical change takes place in the flame test?

There is a change in color

3.) What group, from the periodic table, do these elements exist?

Some of the elements exist in the alkali metals, some in the alkaline metals, and one in the group of other metals.

4.) Do any two elements give the same spectrum of color? Explain why?

Sodium Chloride and aluminum foil give the same color off. The sodium chloride gives the flame a darker yellow color and the aluminum foil does the same. However, the aluminum foil did not just create a different color to the flame, it gave off sparks of fire.

5.) Recall what a catalyst is in a chemical reaction.  What was the catalyst in these reactions?

A catalyst in a chemical reaction is the process that is made in order to change the reactant into the product. The catalyst in this chemical reaction is heat.

Post Lab Questions:

Critical Thinking: In your blog, explain how the data gathered in this lab can be used to solve crimes or convict criminals. Research the topic and use what you discovered in class to write 1-2 paragraphs on answering question.

*Be sure to cite your source.

Flame analysis is based on the physical and chemical principle that atoms—after being heated by flame—return to their normal energy state by giving off the excess energy in the form of light. The frequencies of the light given off are characteristic for each element. Hence, it is used to identify different elements of substances. Since different elements produce different colors when heated with a flame, the colors produced can be compared to known standards and the presence of certain elements in the sample can be confirmed. Flame tests can also be used to determine the presence of metal elements in water by measuring the spectrum produced by the metals exposed to flame. The water is vaporized and then the emissions of the vaporized metals can be analyzed.

However, as useful as it is to forensic analysis, the flame test does not work on all elements. It cannot detect low concentrations of most ions and impurities can greatly affect the test results. For example, sodium is present in most compounds and can colors the flame.

Video Link: http://www.youtube.com/watch?feature=player_embedded&v=3ScNyl943C4

Source: http://21008isabella-csi.blogspot.com/2011/08/flame-test.html