Chemistry Clarity · chemistryclarity.com

The Mole Concept: Flashcards

Revise the key definitions and conversions for moles, molar mass and Avogadro's number.

11 cardsBeginner

11 cards

  1. Question
    What is a mole?
    Answer

    A counting unit for particles. One mole contains 6.022×10236.022 \times 10^{23} particles (atoms, molecules, ions or formula units).

  2. Question
    What is the value of the Avogadro constant, to four significant figures?
    Answer

    NA=6.022×1023N_\text{A} = 6.022 \times 10^{23} mol⁻¹

  3. Question
    What is molar mass?
    Answer

    The mass of one mole of a substance, in g/mol. It has the same number as the atomic or formula mass in u.

  4. Question
    Which formula converts a mass in grams into moles?
    Answer

    n=mMn = \dfrac{m}{M} (moles = mass ÷ molar mass)

  5. Question
    Which formula converts moles into a number of particles?
    Answer

    N=n×NAN = n \times N_\text{A} (particles = moles × 6.022×10236.022 \times 10^{23})

  6. Question
    What is the molar mass of water, HX2O\ce{H2O}? (H = 1.008, O = 16.00)
    Answer

    2(1.008)+16.00=18.022(1.008) + 16.00 = 18.02 g/mol

  7. Question
    What is the mass of one mole of oxygen gas, OX2\ce{O2}? (O = 16.00)
    Answer

    32.00 g. Each OX2\ce{O2} molecule contains two oxygen atoms, so M=2×16.00M = 2 \times 16.00 g/mol.

  8. Question
    How many oxygen atoms are in 1 mol of OX2\ce{O2}?
    Answer

    2 mol of O atoms, which is 1.204×10241.204 \times 10^{24} atoms.

  9. Question
    Do 1 mol of carbon and 1 mol of gold contain the same number of atoms?
    Answer

    Yes, both contain 6.022×10236.022 \times 10^{23} atoms. Their masses differ (12.01 g and 196.97 g) because gold atoms are heavier.

  10. Question
    What is the name of the quantity measured in moles, and its symbol?
    Answer

    Amount of substance, symbol nn. Its unit is the mole (mol).

  11. Question
    How has the mole been defined since 2019?
    Answer

    By fixing the Avogadro constant at exactly 6.022 140 76×10236.022\,140\,76 \times 10^{23} mol⁻¹.