AP Chemistry Flashcards: Moles and Molar Mass
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
Define the mole concept.
The mole concept is a convenient method for counting atoms, molecules, or other specified particles by relating a substance's mass to the number of particles it contains via Avogadro's number.
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Define the mole concept.
The mole concept is a convenient method for counting atoms, molecules, or other specified particles by relating a substance's mass to the number of particles it contains via Avogadro's number.
What is Avogadro's number (NA)?
Avogadro's number is 6.022 x 10^23 mol⁻¹, the constant that links the number of moles in a pure sample to its number of constituent particles.
What mathematical technique is used to convert between quantities like mass, moles, and number of particles?
Dimensional analysis is the primary technique used to perform these calculations, employing conversion factors like molar mass and Avogadro's number.
How would you set up a calculation to find the number of formula units in a 58.44 g sample of NaCl (Molar Mass = 58.44 g/mol)?
First, find moles using n=m/M (58.44g / 58.44 g/mol = 1 mole), then multiply by Avogadro's number to find the 6.022 x 10^23 formula units.
Why is the mole concept necessary for laboratory work?
The mole concept is necessary because individual particles cannot be counted directly, so it provides a practical connection between the measurable mass of a substance and the number of particles reacting.
What are 'constituent particles' in the context of the mole concept?
Constituent particles are the fundamental units of a substance, which can be atoms, molecules, or formula units, depending on the substance.
What two macroscopic and microscopic properties does molar mass quantitatively connect?
Molar mass quantitatively connects the macroscopic property of mass (in grams) with the microscopic property of particle count (via the mole).
What is the relationship between the atomic mass unit (amu) of a particle and the molar mass of that substance?
The average mass of one particle in amu is numerically equal to the molar mass of that substance in grams per mole (g/mol).
Explain the significance of the unit 'mol⁻¹' in Avogadro's number.
The unit 'mol⁻¹' signifies 'per mole,' indicating that Avogadro's number is a conversion factor representing the number of particles contained in one mole of any substance.
What is the formula used to calculate the number of moles (n) from a given mass (m) and molar mass (M)?
The number of moles is calculated by dividing the mass of the substance by its molar mass, represented by the formula n = m/M.