November 2, 2013
5th period
H18
Purpose: To demonstrate and classify the characteristics of a chemical reaction.
Objective: Describe the difference between a physical and chemical change.
Data Table:
Chemical Compounds:
|
Elements Involved:
|
Characteristics:
|
Barium Chloride
|
Barium (Ba)
Chlorine (Cl)
|
Green and Deep Blue
|
Calcium Chloride
|
Calcium (Ca)
Chlorine (Cl)
|
Orange
|
Lithium Chloride
|
Lithium (Li)
Chlorine (Cl)
|
Pink/Purple
(actually red)
|
Potassium Chloride
|
Potassium (K)
Chlorine (Cl)
|
Shortens fire and makes it blue
(actually lilac)
|
Sodium Chloride
|
Sodium (Na)
Chlorine (Cl)
|
Bright Orange
(actually yellow)
|
Strontium Chloride
|
Strontium (Sr)
Chlorine (Cl)
|
Red/Pink
|
Aluminium Foil
|
Aluminum (Al)
|
Extreme Temperature, Sparks, Extends Fire
|
Mystery Substance
|
Lithium (Li)
Barium (Ba)
|
Green, Red, Pink, Blue
|
Analysis questions:
- What indicators (at least 3) determine that a chemical change (or reaction) has occurred?
If energy is absorbed or given off in a reaction, a change in odor, or if a liquid changes into a gas or solid it would indicate a chemical change has occurred.
2. What is emitted when a chemical change takes place in the flame test?
A change of color is emitted when a chemical change takes place in the flame test.
3. What group, from the periodic table, do these elements exists?
Barium, calcium, and strontium are all apart of the alkaline earth metal group. Lithium, potassium, and sodium all are alkaline metals. Aluminum is a poor metal and chlorine is a non-metal.
4. Do any of the two elements give the same spectrum of color? Explain why?
Lithium and strontium give off the same color because they have very similar wavelengths.
5. Recall what a catalyst is in a chemical reaction. What was the catalyst in these reactions?
A catalyst is what gets a reaction started or more so speed the reaction up. The catalyst in these reactions are the open flames giving off heat.
Post Lab Questions:
- 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 this question. *Be sure to cite your sources
Flame tests can be used to identify the elements (by making their wavelengths visible), that make up a substance. Criminal investigators/chemists use this method very often by always referring back to a table of element's color. This is an easier and faster way to identify substances at situations such as murder scenes or a robbed place when policemen have found a suspicious substance or useful evidence on the floor or handle of a door. Chemists can even use this method to see if a person has died of an overdose and even identify the human by running a blood/DNA sample in a flame test.
Sources :
http://www.elderhs.net/staff/jamesme/chemone/ch4electrons/chemch4flametest.pdf
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