2.
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Partner:
Date:
Period:
Flame Test
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Prelab Questions
1. What is the purpose of this lab?
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2. What happens to some electrons in elements when we heat them to high temperatures?
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3. What is a photon?
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4. Which has more energy, red light or blue light?
5. Given the following equation, E=h, where  is the frequency of the light emitted, we can
calculate the energy of the light that is being given off. If h (6.626 x 10-34 Js) is equal to
Planck’s constant, what is the energy of light with a wavelength of 560 nm?
6. What would happen to the energy of the photon if the frequency increases?
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Flame Tests for Metals
CP1~1213
Background
Have you ever wondered why a candle flame is yellow? The characteristic yellow of a candle
flame comes from the glow of burning carbon fragments. The carbon
fragments are produced by the incomplete combustion reaction of the
wick and candle wax. When elements, such as the carbon fragments,
are heated to high temperatures, some of their electrons are excited to
higher energy levels. These excited electrons then fall back to lower
energy levels, releasing excess energy in packages of light called
photons, or light quanta. The color of the emitted light depends on its
energy. Blue light is more energetic than red light, for example. When
heated, each element emits a characteristic pattern of light energies,
which is useful for identifying the element. The characteristic colors of
light produced when substances are heated in the flame of a gas
burner are the basis of flame tests for several elements.
In this experiment, you will perform the flame tests used to identify several metallic elements.
Goals
• Observe the colors emitted by various metal ions.
• Identify metals through flame tests.
Materials
solid copper(II) chloride, CuCl2
solid sodium chloride, NaCl
solid barium chloride, BaCl2
solid lithium chloride, LiCl
Deionized water, H2O
9 Q-tips
solid potassium chloride, KCl
solid calcium chloride, CaCl2
solid strontium chloride, SrCl2
Unknown solid salt
Bunsen burner
Note: Always wear safety goggles when working in the lab.
Do not taste any of the substances or touch them with your hands.
Procedure
As you perform the experiment, record your observations in Table 1.
1. Dip a Q-tip into deionized water. Using metal tongs, place the Q-tip into the flame
of a Bunsen burner. Record your observations, then discard the Q-tip.
2. Dip a clean Q-tip into the deionized water, then dip the wet Q-tip lightly into the
first solid. Using metal tongs, place the Q-tip into the flame of a Bunsen burner.
Record your observations, then discard the Q-tip as directed by your teacher.
3. Repeat Step 2 for each solid, using a clean Q-tip each time. DO NOT RE-USE QTIPS or DOUBLE-DIP THEM.
4. Once you have observed the color of the flame for each of the known solutions,
observe the color of the flame for an unknown solid salt. Can you identify the
metallic ion in the solid?
Fig. b
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Data Table Flame Tests
Solution
(Deionized water)
Cation
Anion
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Flame Color
Sodium chloride, NaCl
Potassium chloride, KCl
Calcium chloride, CaCl2
Barium chloride, BaCl2
Strontium chloride, SrCl2
Lithium chloride, LiCl
Copper (II) chloride, CuCl2
Unknown salt solution
Questions
1) Does the color depend on the cation or the anion? Explain your answer using evidence from the data table.
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2) Would flame tests be useful for detecting metal ions present in a mixture of metal ions? Explain.
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3) List the metallic elements used in the flame tests in increasing order of the energy of the light emitted.
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4) Consider the colors of flames produced by various metal ions. Is there a relationship between the energies
of the light emitted and the positions of the elements in the periodic table?
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