Essential Chemistry Formulas You Need to Know

Here's the thing about chemistry exams - you won't get a formula sheet, so these equations need to be stuck in your head like your favourite song lyrics. The good news? There are only a handful of really important ones.

Atom economy tells you how much of your reactants actually turn into useful products. The formula is: (MR of wanted product ÷ sum of MR of all reactants) × 100. Think of it like measuring how much of your ingredients actually end up in your final cake rather than getting wasted.

For gas calculations, remember that volume = (mass ÷ MR) × 24, which is the same as moles × 24. The mass formula is your absolute best friend: mass = moles × MR. Write this one on your hand if you have to!

Concentration is simply mass or moles divided by volume in dm³. Meanwhile, percentage yield compares what you actually got versus what you predicted: (actual yield ÷ predicted yield) × 100.

Top Tip: When tackling word problems, write all the information into a table with columns for mass, MR, and moles - it makes everything clearer and stops you from getting confused.