Lab 11: Flame Test Lab
Flame Test Lab
Introduction/Pre-Lab:
The purpose of this lab was to observe the effect of certain compounds and more specifically elements in the compounds being burned. Basically, this means trying to find patterns of the flame color when different elements are burned. This was done by putting several known solutions on different wooden splints and putting them over a fire to see the change in color. Then, to test our ability of identifying the compound, we were given two unknown solutions and by observing the flame color when burned, we attempted to predict what compound it really was.
1. What is the difference between ground state and an excited state?
The difference between ground state and excited state is the energy levels. When an element's electrons are at their lowest energy levels available, it is known as the ground state. When an element's electrons absorb some form of energy, their energy levels raise causing the element to be at its excited state where it is considered unstable.
2. What does the word "emit" mean?
The word "emit"means to basically, give off, release or radiate a certain substance or something.
3. In this experiment, where are the atoms getting their excess energy from?
The atoms in this experiment are getting their excess energy from the heat of the burning gas from the bunsen burner. The heat is a type of energy the electrons in the atom are able to use to go to its excited state.
4. Why do different atoms emit different colors of light?
Different atoms emit different colors of light because when the electrons become excited, they jump to higher levels which can differ from atom to atom and when they relax down into their original positions they can give off different amounts of energy which makes different colors. On the spectrum, different amounts of energy represent different colors ranging from violet to red so the atoms can produce different colors.
1. What is the difference between ground state and an excited state?
The difference between ground state and excited state is the energy levels. When an element's electrons are at their lowest energy levels available, it is known as the ground state. When an element's electrons absorb some form of energy, their energy levels raise causing the element to be at its excited state where it is considered unstable.
2. What does the word "emit" mean?
The word "emit"means to basically, give off, release or radiate a certain substance or something.
3. In this experiment, where are the atoms getting their excess energy from?
The atoms in this experiment are getting their excess energy from the heat of the burning gas from the bunsen burner. The heat is a type of energy the electrons in the atom are able to use to go to its excited state.
4. Why do different atoms emit different colors of light?
Different atoms emit different colors of light because when the electrons become excited, they jump to higher levels which can differ from atom to atom and when they relax down into their original positions they can give off different amounts of energy which makes different colors. On the spectrum, different amounts of energy represent different colors ranging from violet to red so the atoms can produce different colors.
(Burning Lithium Chloride, LiCl) (Burning Sodium Carbonate Na2CO3)
Conclusion/Questions:
In conclusion, we were able to quickly and successfully finish the lab with accurate results. Although this lab was fairly simple to test, we were still able to take good observations of the different flame colors which allowed us to predict the two unknown solutions.
2. What patterns do you notice in the groupings?
A pattern we noticed is that certain elements/metal ions correspond to certain colors. An example of this would be that all of the solutions with copper in them ended up turning the flame a blue/green color. This makes sense because when they are heated up, the electrons are the same so their release of light, when dropping from their excited state to ground state, should be the same color.
A pattern we noticed is that certain elements/metal ions correspond to certain colors. An example of this would be that all of the solutions with copper in them ended up turning the flame a blue/green color. This makes sense because when they are heated up, the electrons are the same so their release of light, when dropping from their excited state to ground state, should be the same color.
3. Predict the flame color for a substance called strontium sulfate. Explain your reasoning
The flame color for strontium sulfate would most likely by some kind of reddish orange color because strontium chloride burned this color and as we said before, the metal tends to decide the color of the flame.
The flame color for strontium sulfate would most likely by some kind of reddish orange color because strontium chloride burned this color and as we said before, the metal tends to decide the color of the flame.
4. What evidence do you have that atoms of certain elements produce a flame of a specific color?
The evidence that we have is that when certain metals were placed over the flame, they had the same type of color. As we mentioned before, copper always had a blue/green color and sodium always was an orange color. This makes sense because they are the same atom so the electrons should jump to the same higher levels of energy which means they will be similar flames.
5. Can a flame test be used to identify a metal atom in a compound? Why or why not? What about a nonmetal atom?
Yes, most of the time a flame test can be used to identify a metal because when the metals were burned, they almost always had the same color or at least a similar color stated above. For nonmetal atoms this is not the case because during the experiment there was no correlation between nonmetal and color. This might make sense because because the metal ions which are negative need to gain an extra electron in order to become neutral so they must emit energy in order to do so. Nonmetal ions on the other hand already have at least one more electron than they need so they must loose an electron in order to do so. This would need to be done by absorbing the energy and not emitting it.
6. Identify the two unknowns. What are they and how do you know?
Unknown 1 is LiCl and Unknown 2 is KCl. We know this because when they were burned and given the extra energy, there color matched these two compounds which means that they must be the same.
Unknown 1 and LiCl had the same distinct color of pink while unknown 2 and KCl had the same color of a darker purple. The nonmetal ions can't for sure be identified because they do not play a part in emitting a color.
Unknown 1 and LiCl had the same distinct color of pink while unknown 2 and KCl had the same color of a darker purple. The nonmetal ions can't for sure be identified because they do not play a part in emitting a color.
7. Copper oxide, CuO, is a black solid. It doesn't look at all like the element copper. What color flame would it produce?
The flame color copper(II) oxide would produce would definitely be a blue/green because all metal ions tend to emit the same color when burned. The nonmetal ion doesn't really play a part in giving off color so we known that the oxygen doesn't really matter. This does not only make sense because it is the same electron configuration but we tested in the lab with three different samples/solutions that had copper in them which all burned to be a blue/green.
The flame color copper(II) oxide would produce would definitely be a blue/green because all metal ions tend to emit the same color when burned. The nonmetal ion doesn't really play a part in giving off color so we known that the oxygen doesn't really matter. This does not only make sense because it is the same electron configuration but we tested in the lab with three different samples/solutions that had copper in them which all burned to be a blue/green.
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