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- Conversions
- Mass - Mole - Numbers
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Avogadro's number, the mole concept, formul weights and molar
mass allow us to convert among masses, moles and number of atoms
or molecules. For example suppose we have 25 g of acetic acid
(C2H4O2). The molar mass of acetic acid is 60 g/mol. we can ask
the following questions for 25 g of acetic acid:
We can answer these questions in the following way:
| How
many moles of acetic acid? |
= 25 g x (1 mol acetic acid/60 g) = 0.417 mol |
| How
many moles of carbon? |
=
2x0.417 mol = 0.834 mol of C |
| How many moles of hydrogen? |
= 4x0.417 mol = 1.67
mol of H |
| How many moles of oxygen? |
= 2x0.417 mol = 0.834
mol of O |
| How many total moles of atoms? |
= 8x0.417 mol = 3.34
mol of atoms |
| How many carbon atoms? |
= 0.834 mol x(6.022x10^+23/mol) = 5.02x10^+23 C atoms |
| How many hydrogen atoms? |
= 1.67 mol x(6.022x10^+23/mol) = 1.01x10^+24 C atoms |
| How many oxygen atoms ? |
= 0.834 mol x(6.022x10^+23/mol) = 5.02x10^+23 O atoms |
| How many total atoms? |
= 3.34 mol x(6.022x10^+23/mol) = 2.01x10^+24 total atoms |
Alternatively, we could have started with a number of molecules,
and then convert this number to number of C atoms, mass of C
atoms, moles of C atoms, total moles etc.. The procedure for
this calculation is similar to that above..
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