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NCEA Level 3 Chemistry resource booklet: formulae, complex ions and periodic table

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Formula sheet

The card below opens today's Level 3 Chemistry paper with the sheet in the drawer. The contents follow in our own layout. This is the 2025 booklet, the latest NZQA has published. NZQA's 2026 specification says the booklet will again contain the relevant formulae, the periodic table and a list of nine complex ions.

Formula sheet

NCEA Level 3 Chemistry

Open formula sheet

Thermochemical principles (91390)

n=cVAmount of substance from concentration
n=\frac{m}{M}Amount of substance from mass
q=mc\Delta THeat energy
\Delta_rH^\circ=\frac{-q}{n}Enthalpy change from heat
\Delta_rH^\circ=\Sigma\Delta_fH^\circ(\text{products})-\Sigma\Delta_fH^\circ(\text{reactants})Enthalpy change from formation enthalpies

Equilibrium principles in aqueous systems (91392)

pH=-\log\left[H_3O^+\right]pH
\left[H_3O^+\right]=10^{-pH}Hydronium concentration
K_w=\left[H_3O^+\right]\left[OH^-\right]=1\times10^{-14}Water ionisation constant, at 25 °C
pK_a=-\log K_apKa
K_a=10^{-pK_a}Acid dissociation constant from pKa
K_a=\frac{\left[H_3O^+\right]\left[A^-\right]}{\left[HA\right]}Acid dissociation constant, for HA
K_s=s^2Solubility product, for a salt of type AB
K_s=4s^3Solubility product, for a salt of type A₂B or AB₂
n=cVAmount of substance from concentration
n=\frac{m}{M}Amount of substance from mass

Complex ions for 91392

The booklet lists these nine complex ions, so you do not have to recall their formulae:

Complex ionComplex ion
[Ag(CN)₂]⁻[Ag(NH₃)₂]⁺
[Al(OH)₄]⁻[Cu(NH₃)₄]²⁺
[Pb(OH)₄]²⁻[Zn(OH)₄]²⁻
[Zn(NH₃)₄]²⁺[Ni(NH₃)₆]²⁺
[Ni(CN)₄]²⁻

Periodic table

The last page is a periodic table with element symbols, atomic numbers and molar masses. NZQA's specification says to use the molar masses given with the question or on the table.

What is not on the sheet

  • Any data. Ka values, Ks values, standard enthalpies of formation and bond energies come with the question. NZQA says any context-specific formulae will be provided in the exam. The one constant it names is the specific heat capacity of water, 4.18 J g⁻¹ °C⁻¹, which will be provided when required.
  • Formulae for organic chemistry. 91391 has none, so everything there is recall: functional groups, naming, reactions and isomers.
  • Rearranged versions and the assumptions behind them. The sheet gives Ka as a ratio. It does not tell you when you may treat the acid's concentration as unchanged.
  • Chemical naming conventions. NZQA says the reference sheet on symbols and nomenclature will not be provided in the exam.
  • Which formula to use. It does not tell you whether a question wants Ks = s² or Ks = 4s³.

How to use the sheet in the exam

  1. Write the balanced equation and the quantities given, with units.
  2. Work in moles first: use n = cV or n = m/M, then the ratio in the equation.
  3. Pick the sheet line for the concept: pH, Ka, Ks or enthalpy.
  4. Give the answer to three significant figures with a unit, as NZQA expects.

Equilibrium: the pH of a weak acid

A weak acid HA has a concentration of 0.250 mol L⁻¹ and a pKa of 4.20. Find its pH, assuming the acid barely dissociates, so [HA] stays at 0.250 and [H₃O⁺] = [A⁻]. First turn the pKa into Ka, then use the Ka line:

K_a=10^{-pK_a}=10^{-4.20}=6.31\times10^{-5}\qquad K_a=\frac{\left[H_3O^+\right]^2}{\left[HA\right]}\ \text{so}\ \left[H_3O^+\right]=\sqrt{6.31\times10^{-5}\times0.250}=3.97\times10^{-3}\ \text{mol L}^{-1}
pH=-\log\left(3.97\times10^{-3}\right)=2.40

Equilibrium: solubility

A saturated solution of a salt of type A₂B has a solubility s of 1.5 × 10⁻⁴ mol L⁻¹. The sheet gives Ks = 4s³ for that type, so Ks = 4 × (1.5 × 10⁻⁴)³ = 1.35 × 10⁻¹¹. Write it to three significant figures: 1.35 × 10⁻¹¹.

Moles of solute

The line n = cV needs the volume in litres. For 25.0 mL of 0.200 mol L⁻¹ solution, n = 0.200 × 0.0250 = 5.00 × 10⁻³ mol. Check a quick one now:

practice
Pick an answer, then check it.
A solution has [H3O+] = 1.0 × 10^-3 mol per litre. Which line of the sheet gives its pH, and what is the pH?

The Level 3 sheet and the other chemistry sheets

The Level 2 Chemistry booklet has the same pH and Kw lines and the same n = cV and n = m/M, but no Ka, Ks or enthalpy-of-formation lines. At Level 1 the periodic table in the Chemistry and Biology booklet shows symbols and atomic numbers only. For how the three Level 3 standards work, see the NCEA Level 3 Chemistry guide.

Exam answers

The answers and a worked mark scheme come with today's paper once it is marked. Sit the paper with the booklet open beside you, mark it, and the worked answers show which line each question wanted. We do not publish official or past paper answers. Every question on the daily paper is our own.

Use the sheet with today's paper

Uni-Sine publishes a free daily paper on the NCEA Level 3 Chemistry track. It is a short timed paper of 8 questions worth 25 to 35 marks, not a full NCEA exam, and it is not written by NZQA. Open the sheet from the paper itself and practise choosing the line under a clock.

Common mistakes with the Level 3 Chemistry sheet

  • Using mL in n = cV. Convert to litres first.
  • Dropping the minus sign. pH = −log[H₃O⁺], and a pH of −3 means the minus sign was dropped.
  • Mixing up the two Ks lines. Check the formula of the salt before you pick s² or 4s³.
  • Taking atomic masses from memory. Use the periodic table in the booklet, as NZQA says.

Common questions

Do you get a formula sheet in NCEA Level 3 Chemistry?
Yes. NZQA supplies a Resource Booklet, L3-CHEMR, with the exam. It holds formulae for 91390 and 91392, nine complex ions and a periodic table with molar masses.
When is the 2026 Level 3 Chemistry exam?
Friday 20 November 2026, in the afternoon session, which starts at 2.00 pm.
Is there a periodic table in the Level 3 Chemistry exam?
Yes. NZQA says it is in the resource booklet and gives element symbols, atomic numbers and molar masses.
Does 91391 organic chemistry have formulae on the booklet?
No. The booklet lists formulae for 91390 and 91392 only.

Revision cards

Say the answer first, then flip the card to check it.

Where to go next

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