A student working in an analytical chemistry laboratory must relate the mass of a…
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
A student working in an analytical chemistry laboratory must relate the mass of a substance weighed on a balance to the number of particles present in the sample.
Respond to the following prompts about this mass–particle connection.
(a) Describe what is meant by the term “molar mass” and state its customary units.
(b) Explain how the numerical equality between the average atomic or molecular mass expressed in atomic mass units (amu) and the molar mass expressed in grams per mole enables chemists to convert between macroscopic mass measurements and the number of microscopic particles.
(c) A classmate records a mass of 2.000 g of NaCl and reports that this corresponds to 0.0343 mol. Identify TWO possible sources of error that could make this conversion inaccurate and explain the impact each one would have on the calculated number of moles.