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Colegio de San Juan de Letran

College of Liberal Arts and Sciences Natural Science Area

Scie101 (Physical Science) NAME

RATING

SECTION

DATE

TASK PERFORMED

GROUP NO.

EXPERIMENT 2

Flame Test What you should be able to do At the end of the activity, you should be able to 1. observe the characteristic colors produced by certain metallic ions when vaporized in the flame; 2. identify elements through their characteristic spectra of colors; and 3. appreciate the beauty and order of nature. What you need graduated cylinder concentrated hydrochloric acid (HCl) alcohol burner 0.5 M solutions of nitrates of the following: 8 test tubes Na+ Li+ test tube rack Ca2+ Ba2+ 50-mL beaker K+ Cu2+ wire loop (platinum or nichrome) Sr2+ unknown solution

What you should do Safety Precautions:

Handle concentrated HCl with care. Report all spills at once to your teacher and flush them with cold water and sodium bicarbonate (NaHCO3) solution.

Wear safety goggles to avoid spills to come in contact with the eyes. 1. Pour 5 mL of each of the nitrate solutions in separate test tubes. Label each test tube by indicating

the metallic ion it contains. 2. Pour about 10 mL of concentrated HCl into a 50-mL beaker. To clean the wire loop dip the loop in

the acid and then heat the loop in the outer edge of the burner flame. Continue to clean the loop in this manner until no color is observed in the flame.

3. Dip the clean wire loop into one of the nitrate solutions. Place the loop in the outer edge of the burner flame and move the loop up and down.

4. Clean the wire loop as described in step 2. Repeat step 3 but this time use a different nitrate solution. 5. Test each nitrate solution in the same manner, cleaning the loop thoroughly between tests. Record

all your observations. 6. Obtain a sample of unknown solution. Perform a flame test and identify the metallic ion by the color

of its flame.

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Data and Observations

Metallic Ion

Color of Flame

Ba2+ Ca2+ Cu2+

K+ Li+

Na+ Sr2+

Unknown ________ Let’s Analyze and Interpret 1. Is the flame test an accurate means of identifying a substance? Explain your answer. 2. Explain how the colors observed in the flame tests are produced. 3. Define and relate these terms to the activity:

a. quanta

b. ground state

c. excited state

Give your Generalization ______________________________________ Source: Adapted from De Guzman, Laura and Marie Reyes (2009). Chemistry Work Book. Mandaluyong City: LSGH Work Book. Siraze Chemistry (2005). Lab 18: Flame Test. Retrieved June 16, 2010 from

http://www.siraze.net/chemistry/sezennur/subjects/experiment/018.pdf

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