Unit #1Unit #2Unit #3Unit #4Unit #5Unit #6Unit #7Unit #8Unit #9Unit #10
spacerUNIT # 7  
spacerspacerIntroduction
spacerspacerObjectives
spacerspacerReading

spacer7.1 Calculation of
spacerFormula
spacerMass

spacer7.2 Mole
spacerConcept

spacer7.3 Atomic Mass
spacerRevisited

spacer7.4 Calculation of
spacerMolar Mass
spacer
7.5 Calculations
spacerinvolving
spacerAvogadro #

spacerMass to mole conversion and vice-versa
spacermole to number of particles conversion and vice-versa
spacerMass in grams to number of particles conversion
spacer
7.6 Molar Volume
spacerof a Gas
spacerMolar volume calculations
spacer
7.7 Percent
spacerComposition
spacer
7.8 Empirical
spacerFormula

spacer7.9 Empirical
spacerMass to
spacerMolecular
spacerFormula



spacerProblems
spacer1 | 2
| 3 | 4 | 5

Unit #7 CALCULATIONS BASED ON FORMULAE

7.3 - Atomic Mass Revisited

In section 3.5 we learned about atomic mass and the unit of amu was introduced. Take some time and review before moving on. It is important that you fully understand the concept of atomic mass unit.

Review reading:

Section 4.5
Isotopes ..p85

 

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Go on ... come back to this page when you're ready ... we're in section 7.3 ... I'll wait.

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In section 7.2 we introduced the idea of the mole and told you why we need to scale up to this unit of counting. Now that you have some ideas of just how big a mole of substance (like water) is, we use this scaled up unit of counting in order to refer to a mass of a water molecules that we can physically see. The real neat thing about Avogadro's number is that:

We can equate the numerical quantity of the mass of a single ATOM (in amu) to the mass of a mole of the same atoms (in grams).

For example:

1 carbon atom

has a mass of 12.011 amu.







 
1 mole, or 6.022x 1023, of carbon atoms has a mass of 12.011 grams.

Points to consider:

  • The atomic mass of one atom has units of atomic mass unit, amu.
  • The atomic mass of one mole of atoms has units of grams, g.

Here is another example:

1 sodium atom

has a mass of 22.990 amu.

 







 
1 mole, or 6.022x 1023, of sodium atoms has a mass of 22.990 grams.


Again,

  • The atomic mass of one atom has units of atomic mass unit, amu.
  • The atomic mass of one mole of atoms has units of grams, g.

The units of atomic mass can be:

Section 8.1
Calculation of Mole of Units. Avogadro's Number (N) ..p189

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