Cayla Cornwell
H-18 Period: 5
Purpose:
To demonstrate and classify the characteristics of a chemical reaction.
Objective:
Describe the difference between a physical and chemical change.
Materials Used:
- Barium Chloride
- Calcium Chloride
- Lithium Chloride
- Potassium Chloride
- Sodium Chloride
- Strontium Chloride
- Burner
Data Table:
Chemical Compounds:
|
Elements Involved:
|
Characteristics:
|
Barium Chloride
| Ba | When it merged with the fire the fire turned a light green color. |
Calcium Chloride
| Ca | The fame turned a very bright orange, almost a pumpkin shade. |
Lithium Chloride
| Li | The flame turned a red/ pink color when coming in contact with this solution. |
Potassium Chloride
| K | The flame turned the same blue color as the base of it. |
Sodium Chloride
| Na | This solution caused the flame to turn the color yellow. |
Strontium Chloride
| Sr | This flame was the same pink/red color as the lithium chloride. |
Unknown???
| Li, Ba | The flame held the same characteristics as the Lithium and Barium solutions. |
Analysis Questions:
1.) What indicators (at least 3) determine that a chemical change (or reaction) has occurred?
Three indicators that determine chemical change are when it changes into a new substance that cannot be reversed, change in odor, or when a liquid changes into a gas or a solid.
2.) What is emitted when a chemical change takes place in the flame test?
Change of color is emitted when chemical change takes place in the flame test.
3.) What group, from the periodic table, do these elements exist?
Lithium, sodium and potassium belong to the alkali metals. Barium and strontium belong to the alkali earth metals.
4.) Do any two elements give the same spectrum of color? Explain why?
Yes, because they exist in the same category as the other element that has the same color.
5.) Recall what a catalyst is in a chemical reaction. What was the catalyst in these reactions?
The catalyst in these chemical reactions was heat. Heat caused the flame to turn a different color when combined with the chemicals.
Post-Lab Question
Critical Thinking:
Flame tests can be very useful in convicting criminals or solving crimes. Because each alkali metal gives off a different color when chemically reacting with heat ( and/ or fire), it can be used to identify certain metal samples that are found at a crime scene. It is often used to point out polymers because they give off unique burn marks. When a forensic scientist is given a sample of metal from a crime scene they will most likely use the flame test to identify it.
Works cited:
http://www.cengagesites.com/academic/assets/sites/4827/advancedchapter3.pdf
Video:
http://www.youtube.com/watch?v=Y1LMYP-lJJY
http://www.teachertube.com/viewVideo.php?video_id=215277
