Avogadro’s number (NA)
Definition
Avogadro's number (NA) is the number of constituent particles, usually atoms or molecules, that are contained in one mole of a substance. It is numerically defined as $6.022 \times 10^{23}$ mol$^{-1}$.
5 Must Know Facts For Your Next Test
- Avogadro's number is $6.022 \times 10^{23}$ mol$^{-1}$. This means one mole of any substance contains exactly this many particles.
- It allows chemists to count atoms and molecules by weighing them, bridging the gap between the atomic scale and macroscopic quantities.
- Named after Amedeo Avogadro, who first hypothesized that equal volumes of gases at the same temperature and pressure contain an equal number of molecules.
- Used to convert between moles and number of atoms or molecules in stoichiometric calculations.
- In calculations involving gases, Avogadro’s number helps relate the volume of gas at standard temperature and pressure (STP) to the quantity in moles.
Review Questions
- What is the numerical value of Avogadro’s number?
- How does Avogadro’s number help in converting between moles and individual particles?
- Why is Avogadro's number important for stoichiometric calculations?
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Related terms
Mole: A unit that measures the amount of a substance; one mole contains exactly $6.022 \times 10^{23}$ particles.
Molar Mass: The mass of one mole of a substance (usually expressed in grams per mole).
Stoichiometry: The calculation of reactants and products in chemical reactions using balanced chemical equations.
