A pharmaceutical technician is asked to prepare an aqueous sample that contains…
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
A pharmaceutical technician is asked to prepare an aqueous sample that contains exactly one billion (1.00×10^9) molecules of pure caffeine, C8H10N4O2. Before beginning any arithmetic, the technician pauses to reflect on the conceptual framework that links the mass that will be weighed on an analytical balance to the desired microscopic particle count.
Respond to the prompts below in a well-organized, paragraph-style answer that makes explicit reference to relevant chemical quantities and units.
(a) Describe, in words, the complete logical sequence of quantity conversions that would allow the technician to proceed from a macroscopic mass measurement (in grams) to the required count of individual caffeine molecules. Do not perform any numerical calculations.
(b) Explain why the numerical value of the molar mass expressed in g mol^−1 is equal to the average mass of a single molecule expressed in atomic mass units (amu), and clarify how this equivalence facilitates the conversion path you outlined in part (a).