Overview
Understanding Cambridge 9701 Chemistry command words is the single most effective way to improve your exam performance. These words are direct instructions from the examiner, telling you exactly what type of answer to provide and how much depth is required. By decoding these instructions, you can structure your answers precisely to meet the criteria of the mark scheme, turning your chemical knowledge into marks on the page.
The Foundation: Recall and Precision
For Cambridge syllabus 9701, lower-tariff questions in Papers 2 and 4 use command words that reward accurate recall and conciseness. Define requires a formal, syllabus-perfect definition; for example, defining *standard enthalpy change of atomisation* must include mentions of 'one mole of gaseous atoms' and 'standard conditions'. State asks for a brief, factual answer with no explanation, such as giving the colour of a precipitate. Describe requires a step-by-step account of observations (e.g., 'effervescence was seen') or a practical procedure. Finally, Calculate questions demand that you show all your working, including the formula used, substitution of values, and a final answer with the correct units and significant figures to secure all available point marks.
Building the Argument: Explanation and Application
For Cambridge syllabus 9701, the most common command word you will encounter is Explain. This goes beyond simple recall and asks for the scientific reasoning behind a phenomenon. You must link cause and effect using precise chemical principles. For instance, explaining why magnesium has a higher melting point than sodium requires you to discuss the number of delocalised electrons, the charge on the metal cation, and the resulting strength of the metallic bonding. Another key word is Suggest, which tests your ability to apply knowledge to unfamiliar scenarios. Here, you need to propose a chemically sound reason or outcome based on the principles you have learned, even if it's not something you have explicitly been taught.
Reaching the Top: Analysis and Evaluation
For Cambridge syllabus 9701, high-tariff questions, often worth 4–6 marks, use command words that require higher-order thinking. Analyse asks you to interpret data or information, identify trends and patterns, and relate them to underlying chemical concepts. For example, you might be asked to analyse a set of reaction rate data to determine the order of reaction with respect to each reactant. The most demanding words are Discuss, Evaluate, and Assess. These require you to consider multiple sides of an issue (e.g., the pros and cons of a particular industrial process) and then come to a supported judgement. Simply listing points for and against is not enough; you must weigh the evidence and conclude which factor or argument is the most significant, justifying your choice with chemical reasoning.
The Language of Chemistry: Equations and Mechanisms
For Cambridge syllabus 9701, chemistry has its own specific set of instructions. When asked to Write an equation, you must provide a fully balanced chemical equation. Pay close attention to whether state symbols are required, as they are mandatory for questions on thermodynamics and often carry a specific mark. In organic chemistry, a question asking you to Outline a mechanism requires a precise drawing with curly arrows. Each arrow must start from a region of high electron density (a lone pair or a bond) and point to a region of electron deficiency (an atom or a space where a new bond will form). All dipoles, charges, and relevant lone pairs must be shown, as a single misplaced arrow can invalidate the entire step of a mechanism. The precision demanded by the [9701 marking](/subjects/9701) system leaves no room for ambiguity.
Command Words in Practical Papers (3 & 5)
For Cambridge syllabus 9701, in the practical papers, command words are direct instructions for your work at the bench and your subsequent data processing. Record or Measure means you should write down your raw results to the precision of the measuring instrument (e.g., burette readings to two decimal places, with the last digit being a 0 or 5). Calculate requires you to process this data, showing your working as you would in a theory paper. Questions may also ask you to Identify a source of error or Suggest an improvement. For these, avoid generic answers like 'human error'. Instead, be specific to the experiment, such as 'heat loss to the surroundings during the calorimetry measurement' or 'difficulty in judging the end-point of the titration due to the faint colour change'.
Frequently asked questions
This section covers Frequently asked questions — ranked by what Cambridge examiners return to most often in past papers.
What's the difference between 'Describe' and 'Explain'?
'Describe' asks for what happens. It's an account of observations or a sequence of events (e.g., 'a white precipitate forms'). 'Explain' asks for why it happens. It requires the underlying scientific reasoning, using principles like bonding or kinetics (e.g., 'an insoluble salt is formed because the lattice energy is greater than the hydration enthalpies').
How do I make a 'supported judgement' for an 'Evaluate' question?
After presenting balanced arguments (e.g., pros and cons), your judgement must explicitly state which side is more compelling and why. For example, when evaluating two synthetic routes, you might conclude: "Although Route A has a higher percentage yield, Route B is superior overall because it has a higher atom economy and avoids the use of a toxic solvent."
Do I always need to include state symbols in equations?
If the question asks for them, or if it relates to enthalpy changes (where definitions are under standard states), then yes, they are essential and carry marks. In general inorganic or organic equations, they may not be explicitly penalised if omitted, but it is always best practice to include them. When you mark a paper for practice, always check the mark scheme's policy.