Chapter U1.17, Problem 11E

Interpretation Introduction

Interpretation:

The correct option is to be selected.

Concept introduction:

Different compounds produce different colors in a flame test. Flame test is done by heating a small sample of a compound in a flame such as a Bunsen burner. The color of the flame determines which atom is present in the compound. Each metal atom produces a specific color in the flame test.

Answer to Problem 11E

Correct answer: Option (D)

Explanation of Solution

Reason for correct option:

Each metal atom produces a specific color in the flame test. For example, lithium compounds produce red flame, barium produces green flame, sodium produces orange yellow, copper gives blue - green and calcium gives orange colored flame. Non - metal atoms do not affect the color of the flame.

Both lithium chloride, LiCl, and sodium chloride, NaCl, have chlorine atoms. Since these compounds give different colors, it must be due to different metal atoms. Chlorine is common to both compounds. So it is clear that chlorine does not give any color to the flame. Since ammonium chloride also does not give any color, it means all three atoms; nitrogen, hydrogen and chlorine do not give color. Both sodium chloride and sodium nitrate give same color which indicates that sodium gives color and chlorine, nitrogen and oxygen do not give any color as sodium is common to both compounds.

So, option (D) is correct.

Conclusion

Reasons for incorrect options:

(A) Both lithium chloride, LiCl, and sodium chloride, NaCl, have chlorine atoms. Since these compounds give different colors, it must be due to different metal atoms. Chlorine is common to both compounds. So it is clear that chlorine does not give any color to the flame. Hence this is correct but other options are also true.

(B)Since ammonium chloride does not give any color to the flame; it is clear that all three atoms do not give any color. Hence this is true but other options are also true.

(C) Since both these compounds produce same color, it is clear that chlorine, nitrogen and oxygen do not produce any color. Sodium is common to both compounds so the color must be produced due to sodium atoms. Since other options are also correct, this is not the only correct answer.