Essential IGCSE Chemistry Equations and Formulas: Quick Review Sheet

Mastering the IGCSE chemistry equations list is one of the highest-leverage things a student can do before sitting their exam. Mathematical questions appear across multiple paper sections, and a single forgotten formula can cost marks on an entire multi-part question. This guide consolidates every essential equation into one clear reference so you're never caught searching your memory mid-paper.

The IGCSE chemistry equations list is the set of mathematical relationships students must apply to calculate moles, masses, gas volumes, concentrations, and energy changes across Cambridge CAIE, Edexcel, and AQA specifications. Knowing these formulas by heart, and understanding the correct units, is what separates a Grade 7 paper from a Grade 9.

Why do chemistry equations matter so much?

Mathematical questions in IGCSE Chemistry account for more than 20% of available marks across most exam boards. That's a significant chunk of your grade sitting on whether you can recall and correctly apply a handful of core formulas.

Our tutors regularly see students drop unnecessary marks not because they don't understand the chemistry, but because they confuse units, forget to convert, or apply the wrong equation to a familiar context. The fix is simpler than most students expect: systematic memorisation combined with backward calculation practice.

Forgetting a single balancing step in a mole calculation can invalidate every subsequent part of a question. Examiners award method marks, so showing your working is always worth doing, even if your final answer is wrong.

What is on the essential chemistry formulas sheet?

The table below covers the core mathematical relationships tested in IGCSE Chemistry. These appear across stoichiometry, gas volume, and solution concentration questions at Cambridge IGCSE, Edexcel, and AQA level.

Target Value Needed	Core Mathematical Equation	Standard Measuring Units
Moles from mass	Moles = Mass divided by relative formula mass (Mr)	Mass in grams; Mr is dimensionless
Mass from moles	Mass = Moles multiplied by relative formula mass (Mr)	Measured strictly in grams
Gas volumes (RTP)	Volume = Moles multiplied by 24 dm³	Calculated in decimetres cubed (dm³)
Solution concentration	Concentration = Moles divided by volume of solution	Expressed as mol/dm³
Moles from concentration	Moles = Concentration multiplied by volume	Volume must be in dm³
Percentage yield	Percentage yield = (Actual yield / Theoretical yield) × 100	Expressed as a percentage (%)
Atom economy	Atom economy = (Mr of desired product / Sum of Mr of all products) × 100	Expressed as a percentage (%)

Always convert centimetre cubed (cm³) volumes into decimetre cubed (dm³) before processing any concentration calculation. Divide by 1,000 to convert: 250 cm³ becomes 0.25 dm³. Show every conversion step to claim partial marks if your final answer slips.

How do you calculate moles in IGCSE Chemistry?

The mole calculation is the foundation of IGCSE stoichiometry. Every mass, volume, and concentration question traces back to this single relationship.

To calculate moles from a given mass, divide the mass in grams by the relative formula mass (Mr) of the substance. The Mr is the sum of the relative atomic masses of all atoms in the formula, taken from your periodic table.

Students who begin IGCSE tutoring early in Year 10 tend to find mole calculations become automatic well before the exam. That automaticity frees mental bandwidth for the harder multi-step questions that follow.

Using the mole triangle

A simple triangle diagram helps with recall. Write Mass at the top, Moles and Mr at the bottom. Cover the value you want to find, and the triangle shows the operation. Turning equations into mental shapes like this ensures rapid recall under timed conditions.

Working backwards from a known mass

If a question gives you mass and asks for moles, divide. If it gives moles and asks for mass, multiply. Drilling backward calculations is one of the most effective ways to catch the unit errors that cost marks on otherwise straightforward questions.

How do you calculate gas volumes in IGCSE Chemistry?

Calculating gas volumes in chemistry at IGCSE level uses a fixed molar volume at room temperature and pressure (RTP). At RTP, one mole of any gas occupies 24 dm³.

The equation is: Volume (dm³) = Moles × 24. Rearranged: Moles = Volume ÷ 24. This applies to all gases regardless of their identity, which makes it one of the more forgiving formulas on the paper.

According to Cambridge International Education's published mark schemes, gas volume questions commonly appear as the second or third part of a multi-step stoichiometry question. Getting the mole calculation in part (a) correct is therefore critical to earning marks in parts (b) and (c).

Common gas volume errors to avoid

The most frequent mistake is using 24,000 cm³ instead of 24 dm³ without checking what unit the question asks for. Read the unit in the answer line before you calculate, and convert if needed.

How does the molarity equation work at IGCSE?

Molarity equation revision is essential for students sitting titration and solution chemistry questions. Concentration (mol/dm³) equals moles divided by volume in dm³.

The three-way relationship between concentration, moles, and volume works like the mole triangle. Cover any one of the three values, and the arrangement of the other two tells you the operation. Rearranging gives you: Moles = Concentration × Volume, and Volume = Moles ÷ Concentration.

Titration questions are a reliable source of marks in Cambridge IGCSE and Edexcel papers because the method is consistent. If you know the concentration of one solution and the volumes of both, you can always find the unknown concentration by calculating moles first, then dividing by volume.

Unit conversion is non-negotiable

Every volume in a concentration calculation must be in dm³ before you apply the formula. Exam questions almost always give volumes in cm³ to test whether students remember to divide by 1,000. Memorise this conversion and check it every time.

What other equations appear in IGCSE Chemistry maths?

Beyond moles and concentration, IGCSE maths in chemistry includes percentage yield, atom economy, and energy change calculations. These appear regularly in Higher Tier papers and are worth preparing for explicitly.

Percentage yield

Percentage yield compares how much product you actually obtained against the theoretical maximum. The formula is: (Actual yield ÷ Theoretical yield) × 100. A result below 100% reflects real-world losses from incomplete reactions, evaporation, or filtration.

Atom economy

Atom economy measures how efficiently a reaction uses its starting materials. Calculate it as: (Mr of desired product ÷ Sum of Mr of all products) × 100. Higher atom economy means less waste, which is why it matters in industrial chemistry contexts. AQA and Cambridge IGCSE both test this concept in the context of green chemistry.

Energy change calculations

For thermochemistry questions, students need: Energy (J) = Mass (g) × Specific heat capacity × Temperature change. The specific heat capacity of water (4.18 J/g°C) is usually provided, but knowing it saves time. Bond enthalpy calculations use the rule: Energy in (bonds broken) minus Energy out (bonds formed) equals the overall energy change.

How Talimat can help with IGCSE Chemistry

Working through an IGCSE chemistry equations list on paper is one thing. Applying those equations under timed exam conditions, with confidence, is another. That's where structured IGCSE tutoring makes a measurable difference.

At Talimat, every student is matched with a subject-specialist tutor who holds a relevant degree and has passed a 14-step vetting process. Sessions are live and 1:1, which means your child's tutor identifies exactly which equations they're misapplying and corrects the habit before it costs marks. Online tutoring removes the commute and fits around school timetables across the UAE, KSA, Qatar, and Oman.

Our platform also includes mock exams with detailed feedback, a parent dashboard to track progress, and a dedicated Academic Consultant assigned from day one. Students preparing for Cambridge IGCSE, AQA, or Edexcel chemistry all benefit from the same structured approach: concept first, then calculation, then exam-style practice.

If your child is preparing for their chemistry paper and needs targeted support with calculation questions, contact us to be matched with a tutor in under 10 minutes.

Quick revision checklist before the exam

The following checklist covers the highest-priority actions for the week before your chemistry paper. These steps target the calculation marks most students leave on the table.

• Memorise metric unit conversions before starting any paper
• Drill backward mole calculations to catch rearrangement errors
• Practice converting cm³ to dm³ in every concentration question
• Write out percentage yield and atom economy formulas from memory
• Check the unit on the answer line before calculating
• Show all working, even on steps that feel obvious

These steps won't take long. But doing them consistently in the days before the exam builds the kind of automaticity that keeps calculation errors out of your paper.

Revisit this guide alongside past paper practice and check our blog for subject-specific revision resources covering other IGCSE topics.