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Mole Concept quiz #3

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  • Why do chemists use the mole?
    To relate mass, number of particles, and volume in chemical calculations.
  • Which of the following correctly reflects Avogadro's number?
    6.022×10^23.
  • How many moles are in 5.62 g of water?
    5.62 g ÷ 18.02 g/mol ≈ 0.312 moles.
  • You have 33.6 L of neon gas at STP. How many moles is this?
    33.6 L ÷ 22.4 L/mol = 1.5 moles.
  • How many moles of chloride ions are there in 2 moles of calcium chloride?
    2 moles CaCl2 × 2 Cl^- per formula unit = 4 moles Cl^-.
  • How many moles are in 100.0 g of water?
    100.0 g ÷ 18.02 g/mol ≈ 5.55 moles.
  • How many molecules are in 2.3 moles of oxygen?
    2.3 × 6.022×10^23 = 1.39×10^24 molecules.
  • How many atoms are found in 12 grams (1 mole) of carbon-12?
    6.022×10^23 atoms.
  • What is the value of Avogadro's number?
    6.022×10^23.
  • How many moles of potassium chloride are in a given sample?
    Divide the sample's mass by the molar mass of KCl (74.55 g/mol) to find moles.
  • How many carbon atoms are in one mole of carbon?
    6.022×10^23 atoms.
  • Which of the following is equivalent to a mole of carbon atoms?
    12 grams of carbon-12.
  • Why do chemists use moles?
    To relate mass, number of particles, and volume in chemical reactions.
  • How many atoms are in 0.075 mol of titanium?
    0.075 × 6.022×10^23 = 4.52×10^22 atoms.
  • How many carbon atoms are in 5 moles of ethane (C2H6)?
    5 moles × 2 C per molecule × 6.022×10^23 = 6.022×10^24 atoms.
  • How many particles (atoms) are there in 12 grams of carbon-12?
    6.022×10^23 atoms.
  • What is the numeric value of a mole for atoms or molecules?
    6.022×10^23.
  • How many molecules of ammonia are contained in 10.4 moles of ammonia?
    10.4 × 6.022×10^23 = 6.26×10^24 molecules.
  • What is the total number of atoms in 1.0 mole of CO2?
    1 C + 2 O = 3 atoms per molecule; 1 mole × 3 × 6.022×10^23 = 1.81×10^24 atoms.
  • Which item in data table 1 contains the largest quantity of moles?
    The item with the greatest number of moles listed.
  • How many grams of glucose (C6H12O6) are in 3.55 moles of glucose?
    3.55 × 180.16 g/mol = 639.57 g.
  • What is the number of atoms in a mole of any element?
    6.022×10^23 atoms.
  • If you have 0.5 moles of NaCl, how many formula units do you have?
    0.5 × 6.022×10^23 = 3.01×10^23 formula units.
  • What is the total number of moles of atoms contained in 1 mole of NH3?
    1 N + 3 H = 4 atoms per molecule; 1 mole × 4 = 4 moles of atoms.
  • How many Mg atoms are found in 1.00 mole of MgO?
    1.00 mole of MgO contains 1.00 mole of Mg atoms: 6.022×10^23 atoms.
  • What is the mass of 3.09 × 10^24 atoms of sulfur in grams?
    Moles = 3.09×10^24 ÷ 6.022×10^23 ≈ 5.13 mol; mass = 5.13 × 32.07 g/mol ≈ 164.5 g.
  • How many molecules are in 0.500 moles of H2?
    0.500 × 6.022×10^23 = 3.01×10^23 molecules.
  • What is the number of moles in 432 g Ba(NO3)2?
    432 g ÷ 261.34 g/mol ≈ 1.65 moles.
  • How many moles of copper are in a sample that has a mass of 63.546 grams?
    63.546 g ÷ 63.55 g/mol ≈ 1.00 mole.
  • How many hydrogen atoms are in 35.0 grams of hydrogen gas?
    35.0 g ÷ 2.016 g/mol = 17.36 mol H2; 17.36 × 2 × 6.022×10^23 = 2.09×10^25 atoms.
  • How many molecules are there in 5.0 g of methyl alcohol (CH3OH)?
    5.0 g ÷ 32.04 g/mol ≈ 0.156 mol; 0.156 × 6.022×10^23 ≈ 9.40×10^22 molecules.
  • How many atoms of H are in 2.8 mol N2H4?
    2.8 mol × 4 H per molecule × 6.022×10^23 = 6.75×10^24 atoms.
  • How many molecules are there in 2.30 grams of NH3?
    2.30 g ÷ 17.03 g/mol ≈ 0.135 mol; 0.135 × 6.022×10^23 ≈ 8.13×10^22 molecules.
  • How many moles are there in 17.5 grams of sodium?
    17.5 g ÷ 22.99 g/mol ≈ 0.761 moles.
  • What is the significance of Avogadro’s number? Avogadro’s number is the number of -
    Particles (atoms, molecules, ions, or formula units) in one mole of substance.
  • How many atoms of iron (Fe) are in a sample of 7.38 mol Fe?
    7.38 × 6.022×10^23 = 4.44×10^24 atoms.
  • What does a mole represent?
    A mole represents 6.022×10^23 particles of a substance.
  • How many atoms are in a mole?
    6.022×10^23 atoms.
  • How many molecules (or formula units) are in each sample?
    Multiply the number of moles by 6.022×10^23 to get the number of molecules or formula units.
  • How many moles do 10.0 mg of CO represent?
    10.0 mg = 0.010 g; 0.010 g ÷ 28.01 g/mol ≈ 0.000357 moles.