CCEA A2 Chemistry is won on titration precision, transition metal chemistry and organic nitrogen work. This page shows exactly where the marks sit across all four units, the timing per paper, and the exam habits examiners repeatedly reward or penalise.
閱讀時間 3 分鐘更新於: 2026年9月3日
試卷概覽
卷數
4
總分
310
考試時間
6小時 30分鐘
題型
12
試卷
時間
分數
題數
比重
題型
A2 1: Further physical & organic chemistry
2小時
110
17
35.5%
選擇題, Structured calculations and short answer, Extended response (banded QWC)
選擇題, Structured analysis and structure drawing, Extended response (banded QWC)
A2 3: Practical (hands-on)
1小時 15分鐘
30
3
9.7%
Qualitative test observations and temperature recording
A2 3: Practical theory
1小時 15分鐘
60
4
19.3%
Apparatus drawing and experimental description, Organic synthesis and purification procedure, Quantitative analysis and back titration calculations
評級
A*ABCDEU
計算機規定
A scientific calculator is expected for every paper in this subject. CCEA follows the JCQ rule that applies across all its exams: no calculator with a computer algebra system or symbolic manipulation function, no borrowing a calculator from another candidate, and nothing stored in memory that could be retrieved during the exam, including formulae, notes or text. If your calculator has an exam mode, switch it on. It clears stored data far more reliably than the reset button, which only resets display settings and leaves any stored programs or text in memory.
AO1: AO1: demonstrate knowledge and understanding of scientific ideas, processes, techniques and procedures (33%)
AO2: AO2: apply that knowledge and understanding in theoretical and practical contexts and when handling qualitative and quantitative data (42%)
AO3: AO3: analyse, interpret and evaluate scientific information, ideas and evidence to make judgements and reach conclusions, and to develop and refine practical design and procedures (25%)
用途: Keeps a multi-step redox titration calculation, such as a dichromate-thiosulfate sequence, accurate by carrying an exact value through several stages instead of retyping a rounded one.
使用時機: Any redox or back-titration question with more than one calculation stage and an awkward mole ratio such as 1 to 6.
步驟
Calculate moles at the first stage as normal, then press the memory-store key (M+ or STO) instead of writing down a rounded figure. At the next stage, press memory-recall (MR or RCL) to bring the exact value back and continue from there.
考試提示: This works only with values calculated live in the exam. Nothing may be stored in a calculator's memory before the exam, including formulae or old working, so clear memory and switch on exam mode if your calculator has one before you sit down.
Keep stoichiometric ratios exact with fraction mode
Casio fx-83/85 series (scientific)
用途: Keeps the arithmetic exact through several steps and makes it easier to spot when the wrong ratio has been applied.
使用時機: Any redox or acid-base equation with an awkward stoichiometric ratio that would otherwise need early rounding.
步驟
Enter the ratio using the a-b/c fraction key rather than converting to a decimal straight away, and carry that fraction through the rest of the calculation before converting to a decimal at the final answer line.
考試提示: Use this as an in-exam working method only. A calculator with a computer algebra system or any stored formula list is not permitted under CCEA's rules.
Convert units live before substituting into thermodynamic equations
Casio fx-83/85 series (scientific)
用途: Stops a joule to kilojoule or Celsius to kelvin slip from breaking a \(\Delta G = \Delta H - T\Delta S\) calculation.
使用時機: Any free energy, entropy or enthalpy question where the given units do not already match.
步驟
Before substituting into \(\Delta G = \Delta H - T\Delta S\), do the unit conversion, J to kJ or degrees Celsius to kelvin, as its own calculator step and write the converted value on your answer line before continuing.
考試提示: This is a technique for the exam itself, not something to prepare in advance. Your calculator must be cleared of any stored data or formulae before the exam starts.
常見錯誤
1medium涉及分數: 1Volumetric analysis
Describing a solution as 'clear' when they mean 'colourless', or the other way round.
如何避免: Use colourless for the absence of colour and keep clear for the absence of cloudiness. A solution can be clear and blue at the same time.
2high涉及分數: 2Volumetric analysis
Including a non-concordant rough titre when calculating the mean accurate titre.
如何避免: Only average titres that agree within 0.10 cm3 of each other, and state clearly which values were excluded before giving the mean.
3high涉及分數: 3Enthalpy, entropy and free energy
Mixing joules and kilojoules when substituting into \(\Delta G = \Delta H - T\Delta S\), particularly forgetting entropy is usually given in J per K per mole while enthalpy is in kJ per mole.
如何避免: Convert entropy to kJ per K per mole by dividing by 1000 before substituting, and write that conversion as its own line of working.
4medium涉及分數: 2Carboxylic acids
Omitting a factor of two in dibasic acid or diprotic reactions when calculating reacting quantities in esterification and back titrations.
如何避免: Write the balanced equation first and read the mole ratio directly off it before calculating, rather than assuming a one to one ratio.
5medium涉及分數: 2Transition metals
Missing charges or writing the wrong coordination number for complex ions during ligand substitution reactions.
如何避免: Write the full formula of the complex ion in square brackets with its overall charge before balancing the substitution equation.
6medium涉及分數: 2Nuclear magnetic resonance spectroscopy
Confusing peak integration values with splitting pattern multiplicities in proton NMR spectra.
如何避免: Keep the two separate: integration tells you how many protons sit in an environment, splitting under the n plus 1 rule tells you how many non-equivalent protons are next door.
7medium涉及分數: 3Lattice enthalpy
In Born-Haber cycles, omitting fractional coefficients such as one half for diatomic gaseous halogens or hydrogen, or leaving out state symbols.
如何避免: Balance the equation for one mole of the compound and write full state symbols on every step of the cycle before drawing the arrows.
8high涉及分數: 2Volumetric analysis
In QWC practical descriptions, omitting procedural steps such as rinsing glassware with the solution it will hold, or adding acid dropwise near the titration endpoint.
如何避免: Build a short checklist of standard technique steps for volumetric work and tick through it mentally before writing the answer, not just the chemistry.