Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What term is used for the amount of a substance equal in grams to the sum of the atomic masses?

1. Molar mass

2. Mole

3. Mass number

4. Atomic mass

The correct answer is: Mole

The term that describes the amount of a substance equal in grams to the sum of the atomic masses is known as molar mass. Molar mass is specifically defined as the mass of one mole of a substance, which is numerically equivalent to the average atomic mass of the element measured in grams. It allows for easy conversions between the atomic scale and the macroscopic scale we use in the laboratory setting. While the option referring to "mole" defines a quantity of substance (specifically, 6.022 x 10²³ particles of that substance), it does not directly describe the mass of that substance. Mass number refers to the total number of protons and neutrons in an atom's nucleus and does not provide information about the mass in grams. Atomic mass is the mass of a single atom, typically measured in atomic mass units (amu), which also does not correspond directly to the grams of a substance in a macroscopic context. Molar mass serves as a vital conversion factor in chemistry, linking the micro-world of atoms to the macro-world of grams, making it essential for stoichiometric calculations in chemical reactions.