Lesson Worksheet: Flame Tests Chemistry • 10th Grade
In this worksheet, we will practice identifying the uses of flame tests and the colors produced by alkali, alkaline earth, and other metal atoms during a flame test.
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?
- ASpacing of electron energy levels
- BAtomization energy
- CReactivity with oxygen
- DBond energy
- 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?
- ARubidium
- BLithium
- CCesium
- DPotassium
- ESodium
Q3:
Which of the following terms best describes the color of the flame produced by rubidium salts?
- ABlue
- BYellow
- CViolet red
- DOrange red
- EBlue green
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?
- AThe resulting salts are more flammable.
- BIons in the resulting salts produce more intense colors due to their greater charge.
- CTreatment with hydrochloric acid removes impurities.
- DTreatment with hydrochloric acid displaces anions that could alter the flame color.
- EThe resulting salts are more easily vaporized.
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
- BDry the sampling loop in a hot oven
- CWash the sampling loop with distilled water
- DTest the sampling loop with pH paper
- EPlace the sampling loop in a Bunsen flame
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 spacing of energy levels in the metal atoms
- BThe metal atoms present in the sample
- CThe nonmetal atoms present in the sample
- DThe relative concentrations of metal atoms in the sample
- EThe frequency of the emitted light
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.
- BElements with no visible flame color can be identified.
- CElements with similar flame colors can be differentiated.
- DThe charges of metal ions in a sample can be accurately determined.
- EThe concentrations of metal ions in a sample can be accurately determined.
Q8:
Give the chemical symbols of the two alkaline earth metals that produce orange-red or red flames in a flame test.
- A and
- B and
- C and
- D and
- E and
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
- DRecrystallizing the product
- EClosing the air inlet of the Bunsen burner
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 is difficult to differentiate from the color of the Bunsen flame.
- BThe orange color of the flame is produced by chloride ions.
- CThe alkali metal producing the orange flame may be present as a contaminant.
- DThe orange color of the flame is produced by the solvent.
- EMore than one alkali metal produces an orange flame in a flame test.
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