
CALCULATIONS
BASED ON FORMULAE
7.5  Calculations involving Avogadro's number
As chemists, we need to be able to answers questions of this type:
" How many oxygen atoms are there in 5.0 grams of
Na_{2}CO_{3}?"
" 5 moles of electrons is equivalent to how many
electrons?"
" How much volume does 2.5 moles of CO_{2} gas occupy
at STP?"
Avogadro's
number allows us to carrying out calculations between:
 grams
 moles
 number of particles (eg  these can be # of electrons, # of atoms, # of
ions, # of molecules ... etc ...)
How do we do this?
 In the next section, section 7.5.1 we
will learn how to convert between mass (in grams) and moles.
 In the next section, section 7.5.2
we will learn how to convert between moles and number of particles.
 In the next section, section 7.5.3
we will learn how to convert between mass (in grams) and number of particles.
Place your mouse over the image below to see the content of the
sections diagrammatically. Click on the portion of the image to jump to the
section.
Read on ....
Section 8.2
Calculation
of Moles of Units. Avogadro's Number (N) ..p189
