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 #7CALCULATIONS BASED ON FORMULAE

7.5 - Calculations involving Avogadro's number

7.5.3 - Mass in grams to number of particles conversion

Whenever you want to convert quantities from one unit to another, you need to use the appropriate conversion factor. The conversion factor must have units of the two quantities involved.

To convert between mass in grams and number of particles* it will require two steps as there is not a single quantity that relates these two units.

Step 1: Convert the mass in grams to moles. This step is explained in detail in section 7.5.1.
Step 2:
Convert the calculated quantity from step 1 in moles to the number of particles. This step is explained in detail in section 7.5.2.

* particles can be protons, electrons, atoms, ions, molecules, etc ...


For example:

How many oxygen atoms are there in 5.0 grams of Na2CO3?

These are the steps that I would take to answer the question.

Step 1: How many moles of Na2CO3 are there in 5.0 grams of Na2CO3?
Convert the mass (in grams) to moles (see section 7.5.1) .

Step 2: In this many moles of Na2CO3, as calculated in step 1, how many moles of oxygen atoms are there?
Recall our previous analysis of Na2CO3. See
section 5.9.1 for the number of particles conversion.

Step 3: In this many moles of oxygen, as calculated in step 2, how many oxygen atoms are there?
Convert the moles of atoms to number of atoms (see section 7.5.2) .

Section 8.2
Calculation of Moles of Units. Avogadro's Number (N) ..p189

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