Video Transcript
Which of the following terms best describes the identification of an unknown substance and the determination of its chemical composition? (A) Chemical analysis, (B) functional analysis, (C) physical analysis, (D) qualitative analysis only, or (E) quantitative analysis only.
The type of analysis mentioned in the question describes the identification of a substance and the determination of its chemical composition. So we can immediately rule out option (B), functional analysis, as it is a branch of mathematical analysis and not the answer to this question. There are multiple uses of physical analysis, but none of them are relevant to chemistry. Thus, physical analysis is not relevant to identifying substances and their chemical composition. So option (C), physical analysis, is not the answer to this question.
Let’s now look at the definitions for options (D) and (E), qualitative analysis and quantitative analysis. Qualitative analysis methods are used to identify substances in chemical species, whereas quantitative analysis methods are used to determine the abundances of elements and compounds in chemical samples. As quantitative analysis methods determine abundances, they can determine the mass, percentage composition, or concentration of something, for example. The question asks which of the following terms best describes the identification of an unknown substance, which we now know to be qualitative analysis, and the determination of its chemical composition, which we now know to be quantitative analysis. So the type of analysis mentioned in the question involves both qualitative analysis and quantitative analysis.
But options (D) and (E) are qualitative analysis only or quantitative analysis only. Thus, neither option (D) or (E) can be the answer to this question. The term that encapsulates both qualitative and quantitative analysis is chemical analysis. Chemical analysis includes both qualitative and quantitative analysis. So the answer to the question “Which of the following terms best describes the identification of an unknown substance and the determination of its chemical composition?” is (A) chemical analysis.
