Worksheet: Flame Tests

In this worksheet, we will practice identifying the use of flame tests and the colors produced by alkali, alkaline earth, and other metal atoms.

Q1:

When a salt is placed in the flame of a Bunsen burner, the flame changes color. What feature of the metal ions in the salt determines the color of the flame in this experiment?

  • ABond energy
  • BReactivity with oxygen
  • CAtomization energy
  • DSpacing of electron energy levels
  • ESpacing of nuclear energy levels

Q2:

When performing a flame test, for which alkali metal is cobalt glass used to filter out its flame color?

  • ALithium
  • BPotassium
  • CRubidium
  • DSodium
  • ECesium

Q3:

Which of the following terms best describes the color of the flame produced by rubidium salts?

  • ABlue-green
  • BOrange-red
  • CBlue
  • DViolet-red
  • EYellow

Q4:

Before a compound is analyzed using a flame test, it is typically dissolved in hydrochloric acid. What is the main reason for preparing the sample in this way?

  • ATreatment with hydrochloric acid removes impurities.
  • BThe resulting salts are more flammable.
  • CTreatment with hydrochloric acid displaces anions that could alter the flame color.
  • DThe resulting salts are more easily vaporized.
  • EIons in the resulting salts produce more intense colors due to their greater charge.

Q5:

A student is performing a number of flame tests using a sampling loop made of platinum wire. After each flame test, the sampling loop is washed with hydrochloric acid. What must the student do to ensure the sampling loop is clean before it is used for another flame test?

  • ADry the sampling loop with tissue paper
  • BWash the sampling loop with distilled water
  • CDry the sampling loop in a hot oven
  • DPlace the sampling loop in a Bunsen flame
  • ETest the sampling loop with pH paper

Q6:

To determine the composition of a mixture of elements, a sample of the mixture is dissolved in hydrochloric acid for analysis using a flame test. The emission spectrum from the flame test is measured using a spectroscope. Which of the following parameters cannot be fully determined using this method?

  • AThe relative concentrations of metal atoms in the sample
  • BThe metal atoms present in the sample
  • CThe frequency of the emitted light
  • DThe nonmetal atoms present in the sample
  • EThe spacing of energy levels in the metal atoms

Q7:

Additional data may be obtained by passing the light from a flame test through a spectroscope. Which of the following is not an advantage of this technique?

  • ATrace quantities of an element can be detected.
  • BThe concentrations of metal ions in a sample can be accurately determined.
  • CElements with similar flame colors can be differentiated.
  • DThe charges of metal ions in a sample can be accurately determined.
  • EElements with no visible flame color can be identified.

Q8:

Give the chemical symbols of the two alkaline earth metals that produce orange-red or red flames in a flame test.

  • A M g and B a
  • B S r and B a
  • C C a and B a
  • D C a and S r
  • E M g and S r

Q9:

A student uses a flame test to determine whether the major product of a reaction is a potassium salt. Which of the following would not improve the quality of the test?

  • AViewing the flame through cobalt glass
  • BDissolving the product in hydrochloric acid
  • CWashing the sampling loop in hydrochloric acid before use
  • DClosing the air inlet of the Bunsen burner
  • ERecrystallizing the product

Q10:

When an alkali metal is dissolved in hydrochloric acid and analyzed using a flame test, an intense orange flame is observed. Why might more information be needed to confirm the identity of the metal in the sample?

  • AThe orange color of the flame is produced by chloride ions.
  • BMore than one alkali metal produces an orange flame in a flame test.
  • CThe orange color is difficult to differentiate from the color of the Bunsen flame.
  • DThe alkali metal producing the orange flame may be present as a contaminant.
  • EThe orange color of the flame is produced by the solvent.

Q11:

Which alkali metal most resembles strontium when analyzed using a flame test?

  • ARubidium
  • BSodium
  • CPotassium
  • DLithium
  • ECesium

Q12:

Which alkaline earth metal most resembles copper when analyzed using a flame test?

  • ACalcium
  • BBeryllium
  • CMagnesium
  • DBarium
  • EStrontium

Q13:

Which s-block metal does not produce a colored flame in a flame test?

  • ACesium
  • BBeryllium
  • CRubidium
  • DMagnesium
  • ECalcium

Q14:

The table lists the colors observed for different ranges of visible light wavelengths. The wavelength of a line in a flame emission spectrum can be used to identify the metal ion present in a sample.

Color Red Orange Yellow Green Blue Violet
Wavelength Range (nm) 620–750 590–620 570–590 495–570 450–495 380–450

A metal emits light with a wavelength of 671 nm. What color does the light appear?

  • AYellow
  • BOrange
  • CGreen
  • DRed
  • EBlue

The flame emission spectrum of a material displays an intense line at 589 nm. Which alkali metal is likely to be present in the sample?

  • ASodium
  • BRubidium
  • CLithium
  • DPotassium
  • ECesium

The flame emission spectrum of a material displays an intense line at 554 nm. Which alkaline earth metal is likely to be present in the sample?

  • AStrontium
  • BBeryllium
  • CBarium
  • DMagnesium
  • ECalcium

A sample contains a high concentration of copper salts. In which region of the flame emission spectrum are the most intense lines likely to occur?

  • A 495–570 nm
  • B 450–495 nm
  • C 590–620 nm
  • D 570–590 nm
  • E 620–750 nm

Q15:

Additional data may be obtained by passing the light from a flame test through a spectroscope. Which of the following statements is false?

  • ABoth the measurement and the data analysis can be automated.
  • BEach sample measurement can usually be performed in less than a minute.
  • CElements emit light at unique wavelengths and thus are unlikely to be misidentified.
  • DEvery element emits a single wavelength of light.
  • EIt is difficult to analyze nonmetallic elements using this method.

Q16:

The color of a flame test arises due to the formation of excited atoms at high temperature. Which of the following diagrams best represents an excited lithium atom and the main process responsible for the colored flame?

  • A
  • B
  • C
  • D
  • E

Q17:

What is the chemical symbol of the s-block metal that burns in air with a flame color similar to that shown?

  • A B a
  • B L i
  • C C a
  • D K
  • E S r

Q18:

What is the chemical symbol of the s-block metal that burns in air with a flame color similar to that shown?

  • A B e
  • B N a
  • C M g
  • D C s
  • E R b

Q19:

In which of the following images does the result of the flame test indicate the presence of barium?

  • A
  • B
  • C
  • D
  • E

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