Question

part a
how are the molar mass and empirical formula mass for a compound related?
the molar mass is a whole - number multiple of the empirical formula mass.
the empirical formula mass is a whole - number multiple of the molar mass.
the molar mass can be obtained from the empirical formula mass by multiplication to 6.022×10²³
that are the same concepts.

Explanation:

The empirical formula gives the simplest whole - number ratio of atoms in a compound. The molecular formula is a whole - number multiple of the empirical formula. Since molar mass is based on the molecular formula (mass of one mole of the molecular formula) and empirical formula mass is based on the empirical formula (mass of one mole of the empirical formula), the molar mass \(M\) and empirical formula mass \(E\) are related as \(M = n\times E\), where \(n\) is a positive integer (\(n = 1,2,3,\cdots\)).

The empirical formula mass is not a multiple of the molar mass (as that would imply \(E=n\times M\) which is incorrect). Multiplying the empirical formula mass by \(6.022\times 10^{23}\) (Avogadro's number) gives the mass of \(6.022\times 10^{23}\) formula units of the empirical formula, not the molar mass. Molar mass and empirical formula mass are not the same concepts as the molecular formula (related to molar mass) can be a multiple of the empirical formula.

Answer:

The molar mass is a whole - number multiple of the empirical formula mass.