Worksheet: Masses and Moles

In this worksheet, we will practice using the formula mass of a compound to convert between the mass of material and number of moles present.


Calcium carbonate has the formula CaCO3.

What is the mass of one mole of calcium carbonate to the nearest gram?

What is the mass of one formula unit of calcium carbonate to 3 significant figures?

  • A1.33×10 g
  • B6.03×10 g
  • C1.13×10 g
  • D1.00×10 g
  • E1.66×10 g

Calculate to 3 significant figures the number of moles present in 500 g of pure calcium carbonate.


Which of the following represents the greatest mass?

  • A80 L of oxygen gas at 1.00 bar and 298 K
  • B2.00×10 molecules of oxygen gas
  • C2.00 mol of calcium oxide
  • D3 mol of calcium
  • E110 g of calcium


When 10.00 g of water partially evaporates, 10 water molecules are removed as vapor. Calculate the mass of water remaining.


A packet of an artificial sweetener contains 40.0 mg of saccharin (CHNOS)753, which has the structural formula shown.


Saccharin has a molar mass of 183.18 g/mol.

How many saccharin molecules are there in the packet of artificial sweetener to three significat figures?

  • A1.20×10
  • B1.32×10
  • C1.59×10
  • D1.49×10
  • E2.20×10

How many carbon atoms are there in this quantity of saccharin to three significat figures?

  • A1.54×10
  • B8.40×10
  • C1.12×10
  • D1.05×10
  • E9.21×10


Which of the following is furthest from a mole of atoms?

  • A10.81gB
  • B7.023gLi
  • C79.904gBr2
  • D24.305gMg
  • E15.999gO2


Which of the following is furthest from a mole of molecules/formula units?

  • A100.09 g calcium carbonate
  • B20.01 g hydrogen fluoride
  • C79.90 g bromine gas
  • D154.99 g cobalt(II) sulfate
  • E16.04 g methane


There is approximately 1 g of graphite in a pencil. How many moles of carbon atoms are there in 1.0 g of graphite? Give your answer to three significant figures.


Which of the following has the greatest mass?

  • A1molP4
  • B1molF2
  • C1molS8
  • D1molBr2
  • E1molH2


Which of the following contains the greatest number of moles of oxygen atoms?

  • A2.5molCHCHOH32
  • B1.7molHCO2
  • C1.0molHO2
  • D2.0molCHOH3
  • E1.5molHCOH2

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