Chemical Formulae (Leaving Cert Chemistry): Flashcards

Simplest ratio of atoms in a compound

Actual number of atoms of each element in a molecule

$HO$

$H_2O_2$

Convert % to grams (assume 100g of substance)

Convert grams to moles (÷ by atomic mass)

Find simplest ratio (÷ by smallest moles)

Calculate molar mass of empirical formula

Divide molecular mass by empirical formula mass

Multiply subscripts by the calculated value

% by mass of each element in a compound

$\frac{\text{mass of element in 1 mole}}{\text{molar mass of compound}} \times 100$

How atoms are arranged and bonded in a molecule