Flame Tests - Campuses - Directory：火焰测试校区-目录

1、.Name: _Date: October 19, 2010Period: _Flame Test LabPRE-LAB DISCUSSION: When an electron becomes excited, it will jump to a higher energy level. As the excited electron returns to its ground state, it gives off energy, often in the form of visible light. As in all cases where electrons become excit

2、ed, the flame will only produce color for a few seconds at most. Many elements produce flames of a characteristic color when they come in contact with the flame of the burner. Using this method, scientists can determine some elements of an unknown mixture or solution. The flame test is made by takin

3、g a wooden splint soaked in a chemical of the known element, heating it in a flame, and noting the distinctive color of the flame produced by the vaporized salt. Important vocabulary in this lab includes: Excited State- when an electron gains enough energy to temporarily leave its ground state orbit

4、al and move to an orbital of higher energy. Ground State- the level of energy that an electron will be in when it is not excited. PURPOSE: In this investigation the student will learn to identify selective cations (positive ions) using the flame test. Materials: BaCl2, CaCl2, CuCl2, Fe(NO3)3, KCl, L

5、iCl, NaCl, Sr(NO3)2, Q-tips, beaker, water, Bunsen burner, striker, test tube rackPROCEDURE: ALWAYS wear goggles when working in the laboratory! 1. You should have test tube rack with a set of 10 different chemicals (2 unknown)2. Fill beaker way with deionized water.3. Place 10 Q-tips into the water

6、 to soak.4. Take one Q-tip that was soaking in water and gently dip the Q-tip into the first salt. 5. Be careful not to take too much salt, or else you might drop crystals in the Bunsen burner.6. Put the salt crystals that are on the Q-tip in the Bunsen burner flame.7. Record the color observed in y

7、our data table. 8. Repeat process for each salt, using a new Q-tip for each one. 9. Place cooled Q-tips in the trash.DATA AND OBSERVATIONS :Ion testedName of saltCationAnionFlame Color BaCl2CaCl2CuCl2Fe(NO3)3KClLiClNaClSr(NO3)2Unknown #1Unknown #2CONCLUSION QUESTIONS FOR DISCUSSION:1. Do you think i

8、t is the cation or anion that gives the salts their colors when they are burned in a flame? What is your evidence/reason?2. List the metals used in this lab in increasing order of the energy of the light emitted.3. Sodium ions give off a yellow/orange colored flame when heated. Does this mean that a

9、ll substances that give off a yellow/orange flame when heated contain sodium? Explain your answer. 4. Explain one reason why flame tests are good to identify an ion and one reason why flame tests are NOT a good to identify an ion.5. In this lab, you observed that each element emits a unique (J) colo

10、r of light when heated in a flame. If these light emissions were examined through a prism, you would observe that the emitted light is actually composed of different wavelengths of light that may lie in the violet region, the green region, or the red region of the visible spectrum. Each element has a unique emission spectrum. Research how scientists apply these emission spectra to in