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Calculating Molar Mass quiz #6

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  • What is the mass of 4.32 mol GaI3?
    Mass = 4.32 × 499.44 g = 2,157.6 g.
  • How many grams are in 3.7 moles of Na2O?
    Mass = 3.7 × 61.98 g = 229.33 g.
  • What is the mass in grams of 1.900 × 10^24 iodine atoms?
    Moles = 1.900 × 10^24 / 6.022 × 10^23 = 3.16 mol; mass = 3.16 × 126.90 g = 401.00 g.
  • How many grams of H2O are in 0.2 moles of H2O (molar mass 18.01 g/mol)?
    Mass = 0.2 × 18.01 g = 3.60 g.
  • How many grams are in 11.9 moles of chromium?
    Mass = 11.9 × 51.996 g = 617.78 g.
  • What is the mass in grams of 42.30 moles of LiCl?
    Mass = 42.30 × 42.39 g = 1,793.90 g.
  • What is the mass in grams of 2.57 × 10^25 molecules of I2?
    Moles = 2.57 × 10^25 / 6.022 × 10^23 = 42.7 mol; mass = 42.7 × 253.80 g = 10,844 g.
  • What is the molar mass of 1-butene if 5.38 × 10^16 molecules of 1-butene weigh 5.00 μg?
    Moles = 5.38 × 10^16 / 6.022 × 10^23 = 8.94 × 10^-8 mol; molar mass = 5.00 × 10^-6 g / 8.94 × 10^-8 mol = 55.9 g/mol.
  • What is the mass in grams of 1.02 × 10^24 atoms of manganese (Mn)?
    Moles = 1.02 × 10^24 / 6.022 × 10^23 = 1.69 mol; mass = 1.69 × 54.94 g = 92.85 g.
  • What's the total number of atoms in the molecule Al2(S2O3)3?
    Al2(S2O3)3 contains 2 Al, 6 S, 9 O = 17 atoms.
  • What is the molar mass of an element that has a mass of 10.4 grams and contains 0.129 moles?
    Molar mass = 10.4 g / 0.129 mol = 80.62 g/mol.
  • What is the mass of 1.56 × 10^21 atoms of magnesium in grams?
    Moles = 1.56 × 10^21 / 6.022 × 10^23 = 0.00259 mol; mass = 0.00259 × 24.31 g = 0.063 g.
  • The molar mass of CCl4 is 153.81 g/mol. How many grams of CCl4 are needed to have 5.000 mol?
    Mass = 5.000 × 153.81 g = 769.05 g.
  • The mass of a sample of CaCO3 is 751 grams. How many total atoms are present in this sample?
    Moles = 751 g / 100.09 g/mol = 7.51 mol; atoms = 7.51 × 5 × 6.022 × 10^23 = 2.26 × 10^25.
  • The molecular mass of octane is 114.22 g/mol. What is the mass of 22.05 mol of octane?
    Mass = 22.05 × 114.22 g = 2,520.3 g.
  • A chloride of rhenium contains 63.6% rhenium. What is the formula of this compound?
    The formula is ReCl3.
  • What mass of oxygen forms from 71.89 g CO2? Use the periodic table to find molar masses.
    Moles CO2 = 71.89 g / 44.01 g/mol = 1.63 mol; O mass = 1.63 × 32.00 g = 52.16 g.
  • What is the mass of 4.32 mol GaI3?
    Mass = 4.32 × 499.44 g = 2,157.6 g.
  • A 1.0 mol sample of which of the following compounds has the greatest mass?
    The compound with the highest molar mass has the greatest mass per mole.
  • A student weighed 0.550 g of lithium chloride. How many moles is this?
    Moles = 0.550 g / 42.39 g/mol = 0.0130 mol.
  • How many grams are in 7.8 moles of NaCl?
    Mass = 7.8 × 58.44 g = 456.83 g.
  • What mass (in g) does 3.99 moles of Kr have?
    Mass = 3.99 × 83.80 g = 334.36 g.
  • How many atoms are in one formula unit of the compound FeC5O5?
    FeC5O5 contains 1 Fe, 5 C, 5 O = 11 atoms.
  • How many atoms of H are in 31.30 grams of formaldehyde (CH2O)?
    Moles = 31.30 g / 30.03 g/mol = 1.04 mol; H atoms = 1.04 × 2 × 6.022 × 10^23 = 1.25 × 10^24.
  • The molar mass of NH3 is 17.03 g/mol. How many moles of NH3 are present in 107.1 g?
    Moles = 107.1 g / 17.03 g/mol = 6.29 mol.
  • What mass (in g) does 7.98 moles of Kr have?
    Mass = 7.98 × 83.80 g = 668.72 g.
  • How many formula units are in 3.6 grams of NaCl?
    Moles = 3.6 g / 58.44 g/mol = 0.0616 mol; formula units = 0.0616 × 6.022 × 10^23 = 3.71 × 10^22.
  • Which quantity is equivalent to 39 grams of LiF?
    Moles = 39 g / 25.94 g/mol = 1.50 mol.
  • How many grams of H are in 1.52 grams acetic acid?
    Moles = 1.52 g / 60.05 g/mol = 0.0253 mol; H mass = 0.0253 × 4 × 1.008 g = 0.102 g.
  • How many moles are in 25.3 g of a sample of potassium nitrate (KNO3)?
    Moles = 25.3 g / 101.10 g/mol = 0.250 mol.
  • How many grams of krypton are in 2.00 moles?
    Mass = 2.00 × 83.80 g = 167.60 g.
  • How many grams of Fe2O3 are there in 0.500 mole of Fe2O3?
    Mass = 0.500 × 159.69 g = 79.85 g.
  • What is the mass of 0.750 moles of ammonium chloride (NH4Cl)?
    Mass = 0.750 × 53.49 g = 40.12 g.
  • How many grams are in 0.90 mol Pd?
    Mass = 0.90 × 106.42 g = 95.78 g.
  • How many total atoms of aluminum and oxygen are present in the chemical formula 6Al2O3?
    Each Al2O3 has 2 Al and 3 O; 6 × (2+3) = 30 atoms.
  • How many total atoms are in the formula Al2(CO3)3?
    Al2(CO3)3 contains 2 Al, 3 C, 9 O = 14 atoms.
  • How many grams are in 7.22 moles of water?
    Mass = 7.22 × 18.02 g = 130.13 g.
  • What is the mass of 1.20 × 10^24 atoms of potassium?
    Moles = 1.20 × 10^24 / 6.022 × 10^23 = 1.99 mol; mass = 1.99 × 39.10 g = 77.79 g.
  • What is the total mass in grams of 0.75 mole of SO2?
    Mass = 0.75 × 64.07 g = 48.05 g.
  • How many total valence electrons does the compound CCl4 have?
    CCl4 has 4 × 7 (Cl) + 4 (C) = 32 valence electrons.