IIT/FIELD MUSEUM - High School Transformation Project ...



Up in Flames!Guiding Question/HypothesisGuiding Question: How are fireworks of different colors created?HypothesisChoose from the following Hypotheses. Use the information in the reading portion of the lab document to provide evidence for the hypothesis that you have chosen. You must provide at least 2 pieces of evidence for your hypothesis. All evidence must be factual you may not use personal experience for this assignment.The colors found in fireworks are formed from the metal cations releasing energy in each compound.The colors found in fireworks are formed from the non-metal anions releasing energy in each compound.There is no way to predict what the color of a firework will be.Provide your evidence here:________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Experimental ProceduresPut on safety glasses.At each station you will find the following materials. If any material is missing notify the teacher.Cotton swabs.250 mL beaker labeled tap water.50 mL beaker labeled with the chemical formula and chemical name of the solid compound. 100 mL beaker labeled distilled water. Bunsen burner, butane burner, or alcohol lamp.Matches or lighters.Record the chemical formula and chemical name of the solid compound on the data table provided.Light the Bunsen burner, butane burner, or alcohol lamp and adjust the flame until no yellow appears.Remove one cotton swab from the beaker labeled distilled water. Dip the moisten end of the cotton swab into the beaker containing the solid compound you recorded on the data table. The solid crystal should completely coat the end of the moisten cotton swab.Hold the coated end of the cotton swab in the central portion of the flame. Record the dominant color observed on the data table.Extinguish the cotton swab by placing into the beaker labeled tap water.Repeat steps 3-9 for the other chemical compound.Move to the next station and repeat steps 1-10. Chemical compounds needed for flame test:Chemical FormulaChemical Name CaCl2Calcium chloride dihydrateCa(CH3COO)2Calcium AcetateCu(N03)2Copper (II) nitrate trihydrateCuSO4Copper (II) sulfate pentahydrateLiClLithium chlorideLiNO3Lithium nitrateKClPotassium chlorideKNO3Potassium nitrateNaClSodium chloride (Table salt)NaHCO3Sodium bicarbonate (Baking soda)SrCl2Strontium chlorideSr(N03)2Strontium nitrateMg Magnesium strip – demo only ObservationsUp in Flames! Data TableStationChemical FormulaChemical NameColor of FlameWhat element do you think is responsible for the color?1CaCl2Calcium chloride OrangeCa(CH3COO)2Calcium AcetateOrange2Cu(N03)2Copper (II) nitrateGreenCuSO4Copper (II) sulfateGreen3LiCl Lithium chlorideRedLiNO3Lithium nitrateRed4KClPotassium chlorideVioletKNO3Potassium nitrate Violet5NaClSodium chlorideyellowish -goldNaHCO3Sodium bicarbonateyellowish-gold6SrCl2Strontium chloridered-pinkSr(N03)2Strontium nitratered-pink7 Teacher DemoMgMagnesium (Strip)whiteClaims/Evidence (Conclusions)I claim that the _______________ in fireworks create the different colors. What data from the lab supports your claims? (Choose 2 pieces of data)________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Did this data support or contradict your hypothesis?6. ReadingIntroduction to “Up in Flames!”You have probably seen Fourth of July fireworks, or maybe you have been entertained by them at a White Sox game. Well, here is some chemistry in action. It is the same chemistry that yousee when a few drops of soup or milk spill into the gas flame on your stove. 48831507302500Likewise, chemicals are added to fireplace logs to give the fire interesting colors. When an element is heated, its electrons absorb energy and move from one energy level to a higher one. As they drop back to position they emit energy, in the form of light, and this is the light you are seeing in the firework.In any atom, there are always higher energy levels that are unoccupied. If an electron acquires sufficient energy (from heat, light, or electricity, for example) it can jump to one of the higher energy levels. When this happens, the atom is said to be excited. The "excited" state is unstable though, and that electron drops back to its original position or "ground state", though it may drop through intermediate levels on its way down. Radiant energy is emitted at every drop. The radiant energy emitted as the electron drops back to lower available levels is equal in amount to the difference between the two energy levels. The color of the light emitted corresponds to this energy change. A series of lines is produced for each element because there are many energy level transitions possible. Since every element has a unique electron arrangement, every element produces its own pattern or "spectrograph". These line patterns can be used to identify elements, and this field of study is called spectroscopy.When you heat an element you should see one color, and that element will always produce the same color when heated. The metal cation in an ionic compound is usually the ion that will produce a color. When the metal cations come into contact with heat, like a flame, the electrons become excited and release energy in the form of different colors. This is a combination of all the spectral lines produced by the element's moving electrons. To see individual spectra lines, a spectroscope is used. It splits the flame into its component colors (wavelengths) by means of a light diffraction grating. If time permits, your teacher may allow you to use a spectroscope to observe the flames.7. Analysis/ReflectionWhy do you think that you see different flame colors for different compounds?Notice that some of the different compounds you used produced the same color light. Look carefully at their chemical formulas. Try to match the cation with the color light the compound emits. Fill in the third column of the table if you haven't done so already.What is an observation? State at least one you made in this activity. How do you know it is an observation?What is an inference? State one you made in this lab. How do you know it is an inference and not a guess?Explain how pyrotechnicians can make fireworks that are different colors.What cation could be used to make purple fireworks? Red ones? Yellow ones?How are the pyrotechnicians using previously collected scientific information to do their work?"Neon" advertising signs give off colored light due to the same principle described in this lab except that electricity is used to energize the gases and their electrons, instead of heat. Real neon lights are a reddish-orange in color.What other color "neon" lights have you seen? Explain how they give off light using the chemical principles in this activity. Reread the lab introduction, again if necessaryHow do you think the manufacturer make different colored lights?8. WritingHow did your data from the lab either support or contradict your hypothesis. Fill out the graphic organizer with 2 pieces of data (from your claims section) that support your conclusion. Then explain how those pieces of data either support or contradict your hypothesis. This will be an essay and must be completed following the Fenger Essay Rubric. Write the essay in your Journals. Rewrite your original hypothesis:Was your hypothesis supported or contradicted by your data: (Circle One) Supported ContradictedData 1Data 2Data 3 (Optional)Explanation:ExplanationExplanation: ................
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