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Calculating Molar Mass quiz #5

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이 집합의 용어 (40)

  • What is the mass of exactly 500 sulfur atoms?
    Moles = 500 / 6.022 × 10^23 = 8.30 × 10^-22 mol; mass = 8.30 × 10^-22 × 32.07 g = 2.66 × 10^-20 g.
  • What is the molar mass of CO2?
    The molar mass of CO2 is 44.01 g/mol.
  • What is the total number of atoms in the formula NH3?
    NH3 contains 1 N and 3 H = 4 atoms.
  • What is the formula mass of (NH4)2SO4? 96.07 amu, 114.12 amu, 116.17 amu, 132.17 amu
    The correct formula mass of (NH4)2SO4 is 132.17 amu.
  • What is the molar mass of CHCl3? 48.47 g/mol, 83.92 g/mol, 119.37 g/mol, 121.39 g/mol
    The molar mass of CHCl3 is 119.37 g/mol.
  • Which is the molar mass of H2O? 10.02 g/mol, 16.00 g/mol, 17.01 g/mol, 18.02 g/mol
    The molar mass of H2O is 18.02 g/mol.
  • Which is the formula mass of Na2SO4? 119.06 amu, 125.98 amu, 142.05 amu, 174.12 amu
    The formula mass of Na2SO4 is 142.05 amu.
  • The molar mass of nitrogen (N2) is 28.02 g/mol. What is the mass of 2.00 mol?
    Mass = 2.00 × 28.02 g = 56.04 g.
  • What is the molar mass of NaCl?
    The molar mass of NaCl is 58.44 g/mol.
  • How many atoms of oxygen are in the chemical formula 2Ca(ClO2)2?
    Each Ca(ClO2)2 has 4 O; 2 × 4 = 8 oxygen atoms.
  • What is the molar mass of AuCl3?
    The molar mass of AuCl3 is 303.33 g/mol.
  • What is the mass of 7.00 mol of hydrogen peroxide (H2O2)? 0.206 g, 0.389 g, 126 g, 238 g
    The mass is 7.00 × 34.02 g = 238 g.
  • What is the molar mass of sodium (Na)?
    The molar mass of sodium is 22.99 g/mol.
  • What is the molar mass of Al(NO3)3?
    The molar mass of Al(NO3)3 is 213.00 g/mol.
  • What is the molar mass of table salt (NaCl)?
    The molar mass of table salt is 58.44 g/mol.
  • What is the molar mass of water?
    The molar mass of water is 18.02 g/mol.
  • How many carbon atoms are contained in 2.8 g of C2H4?
    Moles = 2.8 g / 28.05 g/mol = 0.100 mol; C atoms = 0.100 × 2 × 6.022 × 10^23 = 1.20 × 10^23.
  • How many iron atoms are contained in 354 g of iron?
    Moles = 354 g / 55.85 g/mol = 6.34 mol; atoms = 6.34 × 6.022 × 10^23 = 3.82 × 10^24.
  • What is the molar mass of Mg3(PO4)2?
    The molar mass of Mg3(PO4)2 is 262.86 g/mol.
  • 2.00 g of an unknown gas at STP fills a 500. mL flask. What is the molar mass of the gas?
    Use molar mass = mass / moles; moles = volume / molar volume at STP.
  • What is the molar mass for the below molecule? Report your answer to the nearest integer.
    Add the atomic masses of all atoms in the molecule and round to the nearest integer.
  • How many carbon atoms are in 77.28 g of ethane (C2H6)?
    Moles = 77.28 g / 30.07 g/mol = 2.57 mol; C atoms = 2.57 × 2 × 6.022 × 10^23 = 3.10 × 10^24.
  • What is the molar mass of an unknown gas with a density of 4.75 g/L at 3.00 atm and 45.0°C?
    Use the ideal gas law to calculate molar mass: M = (density × RT) / P.
  • How many moles of C3H8 are in 67.8 grams of C3H8?
    Moles = 67.8 g / 44.10 g/mol = 1.54 mol.
  • How many anions are there in 3.50 g of MgBr2?
    Moles = 3.50 g / 184.11 g/mol = 0.0190 mol; anions = 0.0190 × 2 × 6.022 × 10^23 = 2.29 × 10^22.
  • How many moles of CuSO4·5H2O are in 3.10 g?
    Moles = 3.10 g / 249.68 g/mol = 0.0124 mol.
  • How many moles of retinol (C20H30O) are in a given mass?
    Moles = mass / molar mass of C20H30O (286.46 g/mol).
  • What is the charge of the metal in [Fe(NH3)2Br4]2–? Omit the + sign.
    The charge of Fe is +2.
  • How many atoms of oxygen are there in 4875 milligrams of Ca3(PO4)2?
    Moles = 4.875 g / 310.18 g/mol = 0.0157 mol; O atoms = 0.0157 × 8 × 6.022 × 10^23 = 7.56 × 10^22.
  • How many grams of maltose do you need to make 100 mL of a 15% w/v solution?
    15% w/v means 15 g per 100 mL; need 15 g.
  • How many moles of copper(II) sulfate (CuSO4) are in a 0.125 g sample?
    Moles = 0.125 g / 159.61 g/mol = 0.000783 mol.
  • A 42.7 gram sample of potassium nitrate contains how many grams of potassium?
    Percent K = (39.10/101.10) × 100% = 38.7%; mass K = 42.7 × 0.387 = 16.52 g.
  • What mass (in grams) of fructose (C6H12O6) is contained in 125 mL of a 0.500 M fructose solution?
    Moles = 0.500 × 0.125 = 0.0625 mol; mass = 0.0625 × 180.16 g = 11.26 g.
  • What is the molar mass of an unknown gas with a density of 3.55 g/L at 2.00 atm and 55.0°C?
    Use the ideal gas law: M = (density × RT) / P.
  • 0.399 g of an unknown gas at STP fills a 550. mL flask. What is the molar mass of the gas?
    Moles = 0.550 L / 22.4 L/mol = 0.0246 mol; molar mass = 0.399 g / 0.0246 mol = 16.22 g/mol.
  • What is the molar mass of Al2(SO4)3? 150.03 g/mol, 278.03 g/mol, 342.17 g/mol, 450.09 g/mol
    The molar mass of Al2(SO4)3 is 342.17 g/mol.
  • What is the mass of 9.45 mol of aluminum oxide (Al2O3)? 254 g, 709 g, 964 g, 1120 g
    Mass = 9.45 × 101.96 g = 963.5 g; closest is 964 g.
  • What is the mass of 7.00 mol of hydrogen peroxide (H2O2)?
    Mass = 7.00 × 34.02 g = 238 g.
  • What is the mass in grams of 5.90 mol C8H18?
    Mass = 5.90 × 114.22 g = 674.90 g.
  • What is the mass of 0.369 moles of Mg(NO3)2?
    Mass = 0.369 × 148.32 g = 54.71 g.