Ionic compounds do not exist as individual molecules; a formula unit thus indicates the lowest reduced ratio of ions in the compound. A chemical formula shows the kinds and numbers of atoms in the smallest representative unit of a substance. The formula unit is a very important unit of measurement in chemistry.
How do you find the number of representative particles in a substance?
Multiply by Avogadro's Number. Multiply the value obtained in Step 3 by Avogadro's number, which represents the number of representative particles in a mole. Avogadro's number has a value of 6.02 x 10^23. Continuing the example, 2 moles of water x 6.02 x 10^23 particles per mole = 1.20 x 10^24 particles.
What is the representative particles of carbon dioxide?
One mole of carbon dioxide molecules has a mass of 44.01 g, while one mole of sodium sulfide formula units has a mass of 78.04 g. Their molar masses are 44.01 g/mol and 78.04 g/mol, respectively. In both cases, that is the mass of 6.02 × 1023 representative particles.