3.1.6

Moles 1

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Moles

Moles are a measurement of chemical amounts.

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Individual atoms

  • Because atoms and molecules are so small, it is inconvenient to talk about individual atoms.
  • Instead, chemical amounts can be measured in moles.

Moles

  • 1 mole of a substance is 6.02x1023 atoms of that substance.
  • This number is called the Avogadro constant.

Relative Formula Mass (Mr)

The relative formula mass (Mr) of a substance is equal to the mass of 1 mole of that substance (in grams). For an element, this is the same as the relative atomic mass.

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Carbon

  • The mass of 1 mole of carbon is 12 g, which is the same as the relative atomic mass of carbon.
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Carbon dioxide

  • Every carbon dioxide molecule has 1 carbon atom and 2 oxygen atoms:
    • Ar of carbon = 12
    • Ar of oxygen = 16
      • Mr of carbon dioxide = 12 + (2 x 16) = 44

Jump to other topics

1Atomic Structure

2Chemical Bonding

3Quantitative Chemistry

4Chemical Changes

5Energy Changes

6The Rate & Extent of Chemical Change

7Organic Chemistry

8Chemical Analysis

9Chemistry of the Atmosphere

10Using Resources

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