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Mole Concept quiz #7 Flashcards

Mole Concept quiz #7
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  • How many lithium atoms are in a 12.0 g sample?
    12.0 g ÷ 6.94 g/mol ≈ 1.73 mol; 1.73 × 6.022×10^23 ≈ 1.04×10^24 atoms.
  • How many molecules of CH4 are in 48.2 g of this compound?
    48.2 g ÷ 16.04 g/mol ≈ 3.01 mol; 3.01 × 6.022×10^23 ≈ 1.81×10^24 molecules.
  • How many moles of Kr are contained in 398 mg of Kr?
    398 mg = 0.398 g; 0.398 g ÷ 83.80 g/mol ≈ 0.00475 moles.
  • Imagine you have 1 mole of bikes. How many moles of tires do you have?
    2 moles of tires (since each bike has 2 tires).
  • What is the mole fraction of hexane? (Assume ideal behavior.)
    Mole fraction = moles of hexane ÷ total moles in the mixture.
  • How many moles of SO2 contain 8.02 × 10^21 atoms of oxygen?
    8.02×10^21 ÷ 2 = 4.01×10^21 SO2 molecules; 4.01×10^21 ÷ 6.022×10^23 ≈ 0.00666 moles.
  • How many moles of CH3OH are there in 50.0 mL of 0.400 M CH3OH?
    0.050 L × 0.400 mol/L = 0.0200 mol.
  • How many atoms are in 5.80 moles of He?
    5.80 × 6.022×10^23 = 3.49×10^24 atoms.
  • The molar mass of LiF is 25.94 g/mol. How many moles of LiF are present in 10.37 g?
    10.37 g ÷ 25.94 g/mol ≈ 0.400 moles.
  • How many atoms of neon are in 0.378 g of neon?
    0.378 g ÷ 20.18 g/mol ≈ 0.0187 mol; 0.0187 × 6.022×10^23 ≈ 1.13×10^22 atoms.
  • How many moles of atoms are in 9.00 g of 13C?
    9.00 g ÷ 13.00 g/mol ≈ 0.692 moles.
  • How many moles of sodium atoms are there in 3.60 × 10^26 sodium atoms?
    3.60×10^26 ÷ 6.022×10^23 ≈ 598 moles.
  • What is the mole fraction of solute in a 3.35% aqueous solution?
    Mole fraction = moles of solute ÷ (moles of solute + moles of solvent).
  • What is the mole ratio of butane to carbon dioxide?
    The ratio depends on the balanced chemical equation for butane combustion.
  • What quantity in moles of CH3OH are there in 150.0 mL of 0.210 M CH3OH?
    0.150 L × 0.210 mol/L = 0.0315 mol.
  • What is the approximate mole fraction of N2 and O2 in the atmosphere combined?
    N2 ≈ 0.78, O2 ≈ 0.21; combined ≈ 0.99.
  • Which solution has the same number of moles of KCl as 75.00 mL of 0.250 M solution of KCl?
    Any solution with 0.01875 moles of KCl (0.075 L × 0.250 mol/L).
  • How many moles of nitrogen dioxide are in a given sample?
    Divide the sample's mass by 46.01 g/mol to find moles.
  • You have 10.0 g each of Na and another element. Which has more moles?
    The element with the lower molar mass will have more moles in 10.0 g.
  • How many moles of cyclohexanone (molar mass = 98 g/mol) are in 147 g of cyclohexanone?
    147 g ÷ 98 g/mol = 1.50 moles.
  • What is the mass of sodium metal that contains 4.653 × 10^19 Na atoms?
    4.653×10^19 ÷ 6.022×10^23 = 7.73×10^-5 mol; 7.73×10^-5 × 22.99 g/mol ≈ 0.00178 g.
  • How many moles of aluminum are in 3.2 × 10^25 atoms of aluminum?
    3.2×10^25 ÷ 6.022×10^23 ≈ 53.1 moles.
  • How many moles of solute are in 2000 mL of a 1 M solution?
    2.000 L × 1 mol/L = 2.00 mol.
  • How many moles of silver atoms are in the piece of jewelry?
    Divide the mass of the jewelry by 107.87 g/mol to find moles.
  • How many moles are there in 82.5 grams of iron?
    82.5 g ÷ 55.85 g/mol ≈ 1.48 moles.
  • What is the mass of exactly 1 mole of each of the elements?
    The mass is equal to the element's molar mass in grams.
  • How many moles of KF are contained in 347 g of water in a 0.175 M KF solution?
    347 g ÷ 18.02 g/mol = 19.3 L; 19.3 L × 0.175 mol/L = 3.38 mol.
  • How many moles are in 2.5 g of N2? 0.089 moles 0.18 moles 1.3 moles 11 moles
    2.5 g ÷ 28.02 g/mol ≈ 0.089 moles.
  • Which best compares 1 mol of sodium chloride to 1 mol of aluminum chloride?
    Both contain 6.022×10^23 formula units, but have different masses and compositions.
  • Which task most likely involves a calculation that uses moles?
    Determining the amount of reactants or products in a chemical reaction.
  • How many moles of oxygen (O2) are present in 33.6 L of the gas at 1 atm and 0°C?
    33.6 L ÷ 22.4 L/mol = 1.5 moles.
  • What mass of sulfur would have precisely 4.7×10^22 atoms of sulfur?
    4.7×10^22 ÷ 6.022×10^23 = 0.0780 mol; 0.0780 × 32.07 g/mol ≈ 2.50 g.
  • How many molecules are in 13.5 g of sulfur dioxide?
    13.5 g ÷ 64.07 g/mol ≈ 0.211 mol; 0.211 × 6.022×10^23 ≈ 1.27×10^23 molecules.
  • How many sulfur atoms are in 0.45 mol BaSO4?
    0.45 mol × 1 S per formula unit × 6.022×10^23 = 2.71×10^23 atoms.
  • Which of the following operations yields the number of moles of solute?
    Divide the mass of solute by its molar mass.
  • How many atoms of hydrogen (H) are present in 200 molecules of ammonia (NH3)?
    200 × 3 = 600 hydrogen atoms.
  • How many molecules are in 0.16 moles of carbon dioxide?
    0.16 × 6.022×10^23 = 9.64×10^22 molecules.
  • What is the number of moles of beryllium atoms in 36 g of Be?
    36 g ÷ 9.01 g/mol ≈ 4.00 moles.
  • How many moles of chlorine gas are contained in 9.02 × 10^23 molecules?
    9.02×10^23 ÷ 6.022×10^23 ≈ 1.50 moles.
  • How many moles of KI are needed to make 0.50 L of a 0.20 M aqueous solution?
    0.50 L × 0.20 mol/L = 0.10 mol.