How to use the NESA Chemistry data sheet in the HSC exam
The NESA Chemistry data sheet is one of the most under-used tools in the HSC exam. Every student gets a clean copy of it inside the exam booklet. Most students glance at it once and never open it again, then waste minutes trying to remember a formula or a value that is sitting on the second page.
This is a walkthrough of every section, what is in it, and when to use each one.
What the data sheet is
NESA publishes the HSC Chemistry Reference Sheet alongside the exam paper. It is the same document every year. You can download the current version directly from the NESA HSC Chemistry exam page.
The sheet has five sections:
- Useful formulas
- Physical constants
- Standard reduction potentials
- Solubility constants (Ksp values)
- Infrared (IR) absorption table
Plus a periodic table, which is printed on a separate page in the same booklet.
You may write on it during the exam. You should.
Section 1: Useful formulas
This section gives you every formula NESA expects you to apply, including:
- n = m / M (moles, mass, molar mass)
- n = cV (concentration calculations)
- PV = nRT (ideal gas equation)
- q = mcΔT (calorimetry)
- pH = -log[H⁺] and pOH = -log[OH⁻]
- Kw = [H⁺][OH⁻] = 10⁻¹⁴ at 25°C
When to use it: Any quantitative question. Especially titration calculations, gas law problems, and enthalpy questions where students often misremember the formula under pressure.
Common mistake: Trying to recall q = mcΔT from memory and writing it as q = mc/ΔT or forgetting that c (specific heat capacity) is given in J/g/°C, not J/kg/°C, on this sheet.
Section 2: Physical constants
Includes:
- Avogadro's constant, NA = 6.022 × 10²³ mol⁻¹
- Gas constant, R = 8.314 J mol⁻¹ K⁻¹
- Molar volume of gas at 100 kPa and 25°C, Vm = 24.79 L mol⁻¹
- Specific heat capacity of water, c = 4.18 J g⁻¹ K⁻¹
When to use it: Any time you need a constant. Look it up. Do not memorise.
Common mistake: Using molar volume at STP (22.4 L/mol) from a textbook rather than the value on the NESA sheet (24.79 L/mol at 100 kPa and 25°C). NESA marks against the value on its own sheet, not against textbook values.
Section 3: Standard reduction potentials
A table of half-reactions written as reductions, with E° values in volts. Used in Module 5 (electrochemistry) and again in Module 8.
When to use it: Any galvanic cell, electrolytic cell, or spontaneity question.
How to read it:
- The table is ordered from most positive E° at the top (strongest oxidising agents on the left) to most negative E° at the bottom (strongest reducing agents on the right).
- To calculate E°cell, use E°cell = E°cathode − E°anode, where both values are taken straight from the table as written (no flipping signs).
- A positive E°cell indicates a spontaneous reaction.
Common mistake: Reversing the sign of the anode value when you flip the half-equation. Do not. The formula E°cathode − E°anode already accounts for the direction. Flipping the sign and subtracting double-counts.
Section 4: Solubility constants (Ksp values)
A list of Ksp (solubility product) values for selected sparingly soluble ionic compounds at 25°C. These are the salts that will form a precipitate under the right conditions; the smaller the Ksp, the less soluble the compound.
Note: NESA does not give you a solubility rules list or a cation-anion matrix on the sheet. You are expected to know the basic solubility rules from class. The Ksp table is for the quantitative work.
When to use it: Any quantitative precipitation question — calculating ion concentrations at saturation, predicting whether a precipitate forms by comparing the ionic product Q to Ksp, or working through common-ion effect problems. The presence of a compound in this table is itself a hint that it is a likely precipitate.
Common mistake: Forgetting to raise ion concentrations to their stoichiometric powers. For PbI₂: Ksp = [Pb²⁺][I⁻]², not [Pb²⁺][I⁻]. Also confusing Ksp (a constant for a saturated solution) with Q (the same expression evaluated under any conditions); precipitation only occurs when Q > Ksp.
Section 5: Infrared (IR) absorption table
Lists absorption ranges (in cm⁻¹) for common functional groups: O-H, N-H, C=O, C-O, C-H, C≡C, C≡N, etc.
When to use it: Any organic spectroscopy question in Module 8 that gives you an IR spectrum. Look up the ranges, do not guess.
Common mistake: Writing the wrong functional group because the absorption falls in an overlap region (e.g. confusing O-H of an alcohol with O-H of a carboxylic acid). The data sheet gives you both ranges separately. Read them carefully.
The periodic table
NESA's periodic table is printed on its own page and includes:
- Atomic number and atomic mass for every element.
- Electron configuration for the first 36 elements.
- Symbols and full names.
When to use it: Any time you need a molar mass, atomic number, or electron configuration. Do not try to memorise atomic masses to two decimal places. Look them up.
Common mistake: Using rounded atomic masses from memory (e.g. Cl = 35.5) when the question expects the value on the sheet (Cl = 35.45). On a multi-step calculation, the small difference can push your answer outside the accepted range.
Pitfalls and good habits
- Memorise vs look up. Anything on the sheet should be looked up, not memorised. Memory under exam pressure is unreliable. The sheet is not.
- Annotate the sheet. As you read each question, mark which values from the sheet you are about to use. It is your scratchpad.
- Match NESA's values. If a textbook gives you a different value for the same constant, NESA's sheet wins in the exam.
- Practice with it. Sit every past paper with the data sheet open beside you. Get fluent at finding the value you need without scanning.
Where to find the official sheet
The current sheet is available on the NESA Chemistry Stage 6 page under "Assessment and reporting". It is identical year to year, so a copy printed today is good for every HSC exam through 2028.
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