Basic Chemical Calculations
Working out formula mass is your starting point for most chemistry calculations. You'll need to add up the mass of every single atom in a chemical formula - sounds tricky, but it's just careful addition once you know the steps.
Start by writing down the formula (usually given in exam questions), then count how many atoms of each element you've got. Use your data booklet to find the relative atomic mass (RAM) for each element, then multiply and add everything together.
Percentage composition tells you what fraction of a compound is made up of one particular element. Calculate the total mass first, work out how much mass comes from your specific element, then convert to a percentage using the formula: % by mass = (mass of element ÷ total mass) × 100.
Quick Tip: Always double-check your atom counting - it's the most common mistake that trips students up in formula mass calculations.
