Percentage Composition, Empirical and Molecular Formulas (VCE SSCE Chemistry): Flashcards

Proportion of compound's mass from each element as a percentage

$\frac{\text{element mass in 1 mol}}{\text{molar mass}} \times 100$

Simplest whole-number ratio of atoms of each element in a compound

Actual number of atoms of each element present in a molecule

They form crystal lattices, not discrete molecules

$n = \frac{m}{M}$ where $n$=moles, $m$=mass, $M$=molar mass

Each water molecule contains 2 hydrogen atoms - multiply by 2

$\frac{\text{molar mass of compound}}{\text{empirical formula mass}}$

Molecular formula is a whole-number multiple of empirical formula

Assume 100 g of compound; percentages become masses in grams