Which of the following best explains why the empirical formula obtained from…
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Problem
Which of the following best explains why the empirical formula obtained from elemental mass-percent data for a pure compound is independent of the mass of sample analyzed?
(a) Because any impurities present increase in the same proportion as the pure compound when the sample mass is larger, their percentages cancel out, so the empirical formula stays the same.
(b) Because dividing each element’s mass by the total sample mass mathematically removes the effect of sample size, the calculated atom ratios are always identical.
(c) Because NA decreases for small samples and increases for large ones, the mole ratios of the elements remain constant regardless of sample size.
(d) Because the mass percent of each element in a pure substance is fixed by the law of definite proportions, any sample size yields the same atom ratio.