Three sealed vials recovered from a first–year chemistry stockroom each contain…
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
Three sealed vials recovered from a first–year chemistry stockroom each contain exactly 5.00 g of a different elemental solid: magnesium (Mg), aluminum (Al), and iron (Fe).
Assume the samples are pure and at room temperature and pressure.
(a) Rank the three vials from the greatest to the fewest number of atoms present in the sample.
(b) Provide a qualitative justification for the ranking in part (a) that does not rely on a detailed numeric calculation. Your explanation should reference the relationship between sample mass, molar mass, and the mole concept.
(c) A second vial containing 10.00 g of magnesium is discovered. Without performing an exact calculation, compare the number of atoms in this 10.00 g Mg sample with each of the original 5.00 g samples. Clearly state whether each comparison shows “greater than,” “less than,” or “approximately equal,” and justify your reasoning.