VCE · Year 11 · Chemistry · Quantifying and classifying materials live from the app

The mole

Atoms are far too small and too numerous to count one by one, so chemists count them by weighing. The mole is the counting unit: one mole of any substance holds 6.02 × 10²³ particles (Avogadro's constant), and it has a mass in grams equal to the substance's relative mass. Weigh a pure sample, divide by molar mass to get moles (n = m/M), then multiply by 6.02 × 10²³ to get the number of atoms or molecules. This is the real knowscape from knowhere, not a picture of one. Drag it. Watch what actually changes.

chemistry · quantifying and classifying materials · the moledrag it · it is yours

the one idea

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Materials hold too many particles to count and too many molecules to learn one by one, so chemistry groups them. Count particles in moles by weighing, sort molecules into families by their functional group, and write a polymer as its repeating unit. Know the group and the member makes sense.

A scale weighs a heap of a pure substance while a mole bar fills in step, with every whole mole marked at its mass in grams. A close-up shows one particle and its atoms, and the working turns the mass into moles, molecules and atoms.

what you leave with

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Avogadro's constant: one mole of any substance contains 6.02 × 10²³ particles, whether atoms, molecules or formula units.
Amount (n, in mol) of a pure sample of known mass: n = m/M, where M is the molar mass in g/mol, e.g. 18.0 g of water ÷ 18.0 g/mol = 1.00 mol.
Number of particles: N = n × 6.02 × 10²³, so 0.500 mol of carbon is 3.01 × 10²³ carbon atoms.
Atoms versus molecules: 1.00 mol of H₂O is 6.02 × 10²³ molecules but 1.81 × 10²⁴ atoms, because each molecule holds three atoms.
Mass grows with every particle added; the mole is just a convenient count, chosen so one mole weighs the relative mass in grams (12.0 g for carbon).

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this conceptthe moleA scale weighs a heap of a pure substance while a mole bar fills in step, with every whole mole marked at its mass in grams.

built on itstoichiometry of combustionbecause every ratio in a combustion calculation is a mole ratio

built on itmeasuring gasesbecause molar volume is the mole wearing a gas costume

built on itfaraday's lawsbecause charge-to-product conversion runs through moles of electrons

built on itice tablesbecause every row of an ICE table is in moles or their concentrations

the rest of quantifying and classifying materials

3 more, same treatment.

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functional polymers and contemporary applicationsin the appmolar massin the appprotons, neutrons and isotopesin the app

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