Flame Test Lab

The purpose of the flame test lab was to see how different substances reacted when put in a flame. We were trying to see what colors each substance produced when it touched the fire and to match two unknown substances to two known substances by comparing the colors that were produced.

Pre Lab Questions:

What is the difference between ground state and an excited state?
Ground state is when all the electrons in an atom are at their lowest possible energy levels. Excited state is when the electrons in an atom have a higher energy level then their ground state energy level.

In this experiment, where are the atoms getting their excess energy from?
The atoms in this experiment are getting their excess energy from the flame they are interacting with.

Why do different atoms emit different colors of light?
Different atoms emit different colors of light because each atom has it's own unique set of electrons which when are excited produce a color of light. The different mix of energy differences for each atom produces different colors.


Here is a picture of one of the flames we tested:

Analysis Questions:

What patterns do you notice in the groupings?
Most of the solutions containing sodium produced a yellow or red color and the solutions containing copper produced a blue/green color.

What evidence do you have that atoms of certain elements produce a flame of a specific color?
When we grouped the substances based on color, certain elements were only involved in making one specific color no matter what it was mixed with. For example, copper always produced the color blue/green even though it was mixed with chloride, to make one substance, and nitrate, to make a different substance.

Can a flame test be used to identify a metal atom in a compound? Why or why not? What about a nonmetal atom?
A flame test can be used to identify a metal atom in a compound because each metal produces a different unique color, due to each metal's varying electron transitions to different energy levels when heated. A flame test can not be used to identify a nonmetal because their electrons do not undergo excitations, thereby when heated, do not produce a distinct color like the metals do. For example, in our experiment, we had the nonmetal chloride in many of our solutions and when mixed with different metals, produced many colors making it impossible to say which exact color chloride produces.

Identify the two unknowns. What are they and how do you know?
Unknown #1 was Lithium Chloride [LiCl], and we know this because when we heated the unknown substance, it produced a bright pink color that matched the color that LiCl produced when it was heated. Unknown #2 was Potassium Chloride [KCl], and we know this because when we heated the unknown, it produced a purple/lavender color which matched the color that KCl produced when it was heated.

Copper oxide, CuO, is a black solid. It doesn't look at all like the element copper. What color flame would it produce? 
Copper Oxide [CuO] would produce a blue/green flame when heated. This is because the substance has copper in it which, when we did our experiment, every time copper was involved the flame turned blue/green.