This memory aid covers Memory Aids within Moles & Calculations for GCSE Chemistry. Revise Moles & Calculations in Quantitative Chemistry for GCSE Chemistry with 27 exam-style questions and 20 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 11 of 17 in this topic. Use it for quick recall, then test yourself straight afterwards so the memory aid becomes usable in an answer.
🧠 Memory Aids
The formula triangle: Draw a triangle with m (mass) at the top, n (moles) bottom-left, and Mr bottom-right. Cover what you want: cover n → m over Mr → n = m ÷ Mr. Think: "Mr Mole finds the MASS."
For percentage yield: "ACTUAL over THEORETICAL, times a hundred" — A/T × 100. Remember: actual yield is always lower than theoretical in real experiments.
For atom economy: "DESIRED over ALL, times a hundred" — the product you WANT divided by ALL products formed. High atom economy = green chemistry.
Avogadro's number: 6.02 × 10²³ — roughly 600 billion trillion. Think of it as "a million million million million" — impossibly big, which is why atoms are weighed in grams, not counted individually.
Practice questions for Moles & Calculations
One mole of any substance contains how many particles?
Explain why the percentage yield of a reaction is never 100% in practice.