Timothy Johns Christian Howard Wan Huang 10/18/12 Flame Test Lab Introduction Spectroscopy is the study of the electromagnetic radiation emitted or absorbed by atoms and molecules. These studies are very helpful in determining an unknown element, given the fact that all elements burn a different color. The flame colors vary because of the different amounts of energy the elements give off. This lab is made for the learner to determine the identity of two unknown elements. Hypothesis If the color of one of the unknown elements is the same as one of the known elements, then they are the same element.
Materials * Samples of the following metallic salts * calcium chloride * copper chloride * iron chloride * lithium chloride * potassium chloride * sodium chloride * strontium chloride * unknown 1 * unknown 2 * Bunsen burner and accessories * Safety goggles * Lab apron * Splints soaked overnight in distilled water * 250 mL. beaker full of distilled water * Popsicle sticks Procedures 1. Place the end of one of the Popsicle sticks soaked in a solution into the flame from the Bunsen burner. Note color(s) of the flame and the duration of the color.
Immerse the Popsicle stick into the distilled water to fully extinguish it, and then discard it into the trash. 2. Repeat step 1 for each of the remaining salts 3. Repeat step 1 for each of the unknown metals and predict the identity of the unknown metals. Repeat any of the known metals to help with this prediction. Observations The salts all burned different colors and all burned for at least ten seconds. The elements with that burned a color with a high energy level on the electromagnetic spectrum burned the longest. The first unknown burned the same color as the strontium chloride so we determined that they were the same element.
The second unknown burned the same color as copper chloride so we determined that they were the same element. Data Table Formula| Metal| Color Observed| CaCl2| Calcium Chloride| Orange| CuCl| Copper Chloride| Green| FeCl3| Iron Chloride| Sparkle| LiCl| Lithium Chloride| Red/Pink| KCl| Potassium Chloride| Purple| NaCl| Sodium Chloride| Yellow| SrCl2| Strontium Chloride| Red| Unknown 1| Strontium Chloride| Red| Unknown 2| Copper Chloride| Green| Analysis 1. What was (were) the identity of the metal ion(s) in the unknown solutions? Give evidence.
Unknown 1 and strontium chloride are the same element because they burned the color. Unknown 2 and copper chloride are the same element because they burned the same color. 2. Predict the flame color metallic ions of copper and strontium were mixed. The flame color would probably be yellow. 3. Based on the flame colors in this experiment, which single element would most likely be used to produce yellow fireworks? Why? Sodium chloride would be used because it burned with a yellow flame. 4. Why do the metals give off light? 5. Which of the flames that you observed gave off the most energy?
Potassium chloride gave off the most energy because purple gives off the most energy. 6. Why do some of the samples give off more than one color flame? Because they are compounds and they have more than one element in them. Conclusion What were your sources of error and how could you fix it for next time to reduce error? Was your hypothesis supported or refuted? Explain. Two sources of error were that the Bunsen burner caught on fire and that there was a lot equipment involved. The hypothesis was supported as far as we can tell because both unknowns burned the same color as one of the known elements.