Which statement about molar mass is true?

Which statement about molar mass is true?

• A. It is the mass of one mole of a substance in grams
• B. It is the number of particles in a mole
• C. It is the volume of one mole
• D. It is always 6.02

Answer: (A)

Molar mass is the mass per amount of substance, expressed in grams per mole. It tells you how heavy one mole of a substance is, not how many particles or how much space it takes up. You find it by summing the atomic masses of all atoms in the formula, giving a mass that is numerically equal to the atomic mass in amu but with units of g/mol. For example, one mole of carbon-12 weighs exactly 12.00 g, illustrating that molar mass is a mass value tied to amount. Avogadro’s number (the 6.02×10^23 particles per mole) and molar volume (about 22.4 L per mole at STP) relate to quantity and space, not mass, so they aren’t the molar mass.

Molar mass is the mass per amount of substance, expressed in grams per mole. It tells you how heavy one mole of a substance is, not how many particles or how much space it takes up. You find it by summing the atomic masses of all atoms in the formula, giving a mass that is numerically equal to the atomic mass in amu but with units of g/mol. For example, one mole of carbon-12 weighs exactly 12.00 g, illustrating that molar mass is a mass value tied to amount. Avogadro’s number (the 6.02×10^23 particles per mole) and molar volume (about 22.4 L per mole at STP) relate to quantity and space, not mass, so they aren’t the molar mass.