{"id":35015,"date":"2026-03-13T14:17:02","date_gmt":"2026-03-13T07:17:02","guid":{"rendered":"https:\/\/times.edu.vn\/?p=35015"},"modified":"2026-03-30T15:24:36","modified_gmt":"2026-03-30T08:24:36","slug":"igcse-chemistry-explain-questions","status":"publish","type":"post","link":"https:\/\/times.edu.vn\/en\/igcse\/igcse-chemistry-explain-questions\/","title":{"rendered":"IGCSE Chemistry &#8220;Explain&#8221; Questions 2026: How to Write Clear, High-Scoring Answers"},"content":{"rendered":"<p><a href=\"https:\/\/times.edu.vn\/en\/igcse\/what-is-igcse-a-comprehensive-guide-for-students\/\">IGCSE<\/a>\u00a0Chemistry <strong>&#8220;explain&#8221; questions<\/strong>\u00a0are best answered by showing clear chemical reasoning: State the key concept, describe the particle-level mechanism, then justify the observable result using precise scientific terminology.<\/p>\n<p>High-scoring responses consistently link <strong>kinetic theory<\/strong>\u00a0and <strong>collision theory<\/strong>\u00a0to reaction rates, connect <strong>molecular structure<\/strong>\u00a0and <strong>intermolecular forces<\/strong>\u00a0to properties, and explain periodic trends through shielding and nuclear attraction.<\/p>\n<p>For multi-mark items, structure your answer as separate, mark-ready points rather than long paragraphs. This approach turns \u201cwhy\/how\u201d prompts into logical, evidence-based explanations that examiners can award marks for quickly and reliably.<\/p>\n<h2><strong>Perfecting Your IGCSE Chemistry &#8220;explain&#8221; questions Strategy<\/strong><\/h2>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-35044\" src=\"https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/03\/5-10.webp\" alt=\"IGCSE Chemistry \u201cExplain\u201d Questions 2026: How to Write Clear, High-Scoring Answers\" width=\"1000\" height=\"558\" srcset=\"https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/03\/5-10.webp 1000w, https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/03\/5-10-300x167.webp 300w, https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/03\/5-10-768x429.webp 768w\" sizes=\"auto, (max-width: 1000px) 100vw, 1000px\" \/><\/p>\n<p>IGCSE Chemistry <strong>&#8220;explain&#8221; questions<\/strong>\u00a0reward students who can show <strong>chemical reasoning<\/strong>, not students who can recite isolated facts. Your job is to connect a visible outcome (colour change, melting, faster rate) to a particle-level cause using <strong>scientific terminology<\/strong>\u00a0and a logically ordered justification.<\/p>\n<p>Based on our years of practical tutoring at Times Edu, the highest-scoring answers behave like short \u201cmini-proofs.\u201d They name the correct concept, link it to the structure\/particles involved, and finish with a clear cause-and-effect statement that matches the command word <strong>Explain<\/strong>: \u201csay why\/how and support with relevant evidence.\u201d<\/p>\n<h3><strong>What makes &#8220;explain&#8221; questions different in the Cambridge marking logic<\/strong><\/h3>\n<p>A critical detail most students overlook in the 2026 exam cycle is that Cambridge <sup><a href=\"#tooltip-ref-1\" class=\"tooltip-link\" data-tooltip=\"https:\/\/www.cambridgeinternational.org\/\">[1]<\/a><\/sup>\u00a0explicitly weights the syllabus toward: <strong>AO1 Knowledge with understanding (50%)<\/strong>\u00a0and <strong>AO2 Handling information and problem-solving (30%)<\/strong>. &#8220;explain&#8221; questions sit right on that boundary: You must know the science (AO1) and use it to produce a reasoned explanation(AO2).<\/p>\n<p>From our direct experience with international school curricula, students who plateau at a \u201cmid B\u201d level usually have enough content knowledge. What they lack is the disciplined habit of turning that knowledge into a structured explanation under time pressure.<\/p>\n<h3><strong>The 3-link chain you should use for most IGCSE chemistry &#8220;explain&#8221; questions<\/strong><\/h3>\n<p>Use this template until it becomes automatic.<\/p>\n<ul>\n<li><strong>Link 1 (Identify the concept):<\/strong>\u00a0Name the correct topic: <strong>K<\/strong><strong>inetic theory<\/strong>, <strong>molecular structure<\/strong>, <strong>intermolecular forces<\/strong>, <strong>collision theory<\/strong>, bonding type, electron configuration, or equilibrium.<\/li>\n<li><strong>Link 2 (State the particle-level mechanism):<\/strong>\u00a0Describe what particles\/ions\/electrons do.<\/li>\n<li><strong>Link 3 (Justify the observation):<\/strong>\u00a0Explicitly connect the mechanism to what the question asks.<\/li>\n<\/ul>\n<p>Keep each link short and concrete. Examiners award marks for distinct scientific points, not for long storytelling.<\/p>\n<h3><strong>A compact table of \u201ccommand word discipline\u201d<\/strong><\/h3>\n<p>Cambridge defines <strong>Describe<\/strong>\u00a0as giving characteristics\/features, while <strong>Explain<\/strong>\u00a0requires reasons\/relationships supported with evidence. That difference should dictate your sentence design.<\/p>\n<table>\n<tbody>\n<tr>\n<th colspan=\"1\" rowspan=\"1\"><strong>Command word<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>What examiners expect<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Common student mistake<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Fix that wins marks<\/strong><\/th>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Describe<\/td>\n<td colspan=\"1\" rowspan=\"1\">Observable features, what happens<\/td>\n<td colspan=\"1\" rowspan=\"1\">Adds \u201cbecause\u201d without a mechanism<\/td>\n<td colspan=\"1\" rowspan=\"1\">Use neutral language: Colour, gas, temperature change<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Explain<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cWhy\/how\u201d with particle-level cause<\/td>\n<td colspan=\"1\" rowspan=\"1\">Repeats the observation as a reason<\/td>\n<td colspan=\"1\" rowspan=\"1\">Add mechanism: Forces, electrons, collisions, energy<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Compare<\/td>\n<td colspan=\"1\" rowspan=\"1\">Similarities and differences<\/td>\n<td colspan=\"1\" rowspan=\"1\">Only differences<\/td>\n<td colspan=\"1\" rowspan=\"1\">Use paired sentences: \u201cBoth\u2026, but\u2026\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Deduce<\/td>\n<td colspan=\"1\" rowspan=\"1\">Conclusion from data<\/td>\n<td colspan=\"1\" rowspan=\"1\">Recalls memorized facts<\/td>\n<td colspan=\"1\" rowspan=\"1\">Quote the evidence (trend\/data) then infer<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3><strong>Why you should care about grade thresholds (without obsessing over them)<\/strong><\/h3>\n<p>Grade thresholds shift by session because they are set after marking, and Cambridge publishes them per series.<\/p>\n<p>Use thresholds to calibrate realism, not to predict your future grade. For example, in June 2024 and June 2025, overall thresholds for the same option (e.g., BX out of 200) differed, which is normal and exactly why you train skill, not luck.<\/p>\n<p><strong>Practical takeaway:<\/strong>\u00a0When you practise past papers, score yourself and then re-mark your <strong>explain<\/strong>\u00a0answers for \u201cmissing links.\u201d A student can gain 10\u201320 raw marks by improving justification alone, even if their factual recall is already strong.<\/p>\n<h3><strong>Choosing subjects strategically for study-abroad profiles<\/strong><\/h3>\n<p>The pedagogical approach we recommend for high-achievers is to treat IGCSE Chemistry as a platform subject\u00a0that strengthens later IB\/A-Level\/AP science. Cambridge itself notes that Chemistry builds foundational knowledge and progression readiness.<\/p>\n<p>If your target pathway includes Medicine, Engineering, Biological Sciences, or Environmental Science, Chemistry is rarely optional. Your profile gains credibility when grades are paired with evidence of scientific thinking: Lab reports, research posters, competitions, or supervised projects that show structured reasoning.<\/p>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/ace-igcse-chemistry-master-stoichiometry\/\">Ace IGCSE Chemistry<\/a>: Master Stoichiometry<\/p>\n<h2><strong>Using Particle Theory To Explain Rates Of Reaction<\/strong><\/h2>\n<p>Most IGCSE chemistry &#8220;explain&#8221; questions on rates are testing whether you can translate <strong>kinetic theory<\/strong>\u00a0into <strong>collision theory language<\/strong>. You must show: Particles move, collide, and only successful\u00a0collisions lead to reaction.<\/p>\n<h3><strong>The \u201crate = success frequency\u201d explanation model<\/strong><\/h3>\n<p>Build rate explanations around one sentence you can adapt.<\/p>\n<ul>\n<li><strong>Rate increases when<\/strong>\u00a0the frequency of successful collisions per second\u00a0increases.<\/li>\n<li><strong>Successful collisions increase when<\/strong>\u00a0particles collide more often and\/or more collisions have enough energy to overcome activation energy.<\/li>\n<\/ul>\n<p>This prevents vague answers like \u201cit reacts faster because it is hotter,\u201d which earn fewer marks unless you justify the particle behaviour.<\/p>\n<h3><strong>Temperature explanations that score full marks<\/strong><\/h3>\n<p>Use a tight mechanism.<\/p>\n<ul>\n<li>Higher temperature means particles have higher average kinetic energy (<strong>kinetic theory<\/strong>).<\/li>\n<li>Particles move faster, so collision frequency increases.<\/li>\n<li>A larger fraction of collisions exceed activation energy, so more collisions are successful.<\/li>\n<li>Therefore the reaction rate increases.<\/li>\n<\/ul>\n<p>Avoid the misconception: \u201cheat acts as a catalyst.\u201d Temperature changes kinetic energy; catalysts change pathways.<\/p>\n<h3><strong>Concentration and pressure explanations using the same logic<\/strong><\/h3>\n<p>For concentration (solutions) and pressure (gases), focus on particle density.<\/p>\n<ul>\n<li>Higher concentration\/pressure means more particles per unit volume.<\/li>\n<li>Particles are closer together, so collision frequency increases.<\/li>\n<li>Therefore the rate increases.<\/li>\n<\/ul>\n<p>If the question asks \u201cwhy the effect is bigger for gases,\u201d mention compressibility and spacing of particles. That is particle-level justification.<\/p>\n<h3><strong>Surface area explanations: <\/strong><strong>M<\/strong><strong>ake the \u201cexposed particles\u201d explicit<\/strong><\/h3>\n<p>Students often stop at \u201cmore surface area.\u201d That is not a reason.<\/p>\n<p>A better chain:<\/p>\n<ul>\n<li>Smaller pieces have greater surface area-to-volume ratio.<\/li>\n<li>More reactant particles are exposed at the surface.<\/li>\n<li>More collisions occur per second at the interface.<\/li>\n<li>Therefore the rate increases.<\/li>\n<\/ul>\n<h3><strong>Catalysts: <\/strong><strong>T<\/strong><strong>he mark-winning version<\/strong><\/h3>\n<p>A catalyst explanation must mention activation energy and alternative pathways.<\/p>\n<ul>\n<li>Catalysts provide an alternative reaction pathway with lower activation energy.<\/li>\n<li>A larger fraction of collisions have enough energy to be successful.<\/li>\n<li>Therefore the rate increases, while the catalyst is not used up overall.<\/li>\n<\/ul>\n<p>This matches the \u201cexplain\u201d definition: Make relationships clear, support with evidence-level concepts.<\/p>\n<h3><strong>Quick table: <\/strong><strong>C<\/strong><strong>ommon rate misconceptions and corrections<\/strong><\/h3>\n<table>\n<tbody>\n<tr>\n<th colspan=\"1\" rowspan=\"1\"><strong>Misconception<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Why it loses marks<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Replacement statement (high-scoring)<\/strong><\/th>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">\u201cHotter = particles collide harder\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\">Vague and unquantified<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cHigher kinetic energy increases collision frequency and the fraction above activation energy.\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">\u201cCatalyst gives energy\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\">Incorrect mechanism<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cCatalyst lowers activation energy via an alternative pathway.\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">\u201cMore surface area = faster\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\">Incomplete justification<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cMore exposed particles increases collision frequency at the surface.\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">\u201cHigher concentration makes particles move faster\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\">Wrong variable<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cHigher concentration increases particles per unit volume, so collisions are more frequent.\u201d<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/struggling-with-igcses-how-to-improve-grades-fast\/\">Struggling with IGCSEs<\/a>? How to Improve Grades Fast 2026<\/p>\n<h2><strong>Linking Bonding Types To Physical Properties Of Substances<\/strong><\/h2>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-35046\" src=\"https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/03\/6-10.webp\" alt=\"IGCSE Chemistry \u201cExplain\u201d Questions 2026: How to Write Clear, High-Scoring Answers\" width=\"1000\" height=\"558\" srcset=\"https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/03\/6-10.webp 1000w, https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/03\/6-10-300x167.webp 300w, https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/03\/6-10-768x429.webp 768w\" sizes=\"auto, (max-width: 1000px) 100vw, 1000px\" \/><\/p>\n<p>High-value IGCSE chemistry &#8220;explain&#8221; questions repeatedly test whether you can connect <strong>molecular structure<\/strong>\u00a0and bonding to melting point, boiling point, conductivity, and solubility. The scoring pattern is consistent: Name the bonding, name the forces, explain the energy requirement.<\/p>\n<h3><strong>The three bonding \u201clanguages\u201d you must not mix up<\/strong><\/h3>\n<ul>\n<li><strong>Ionic structure:<\/strong>\u00a0Lattice, ions, strong electrostatic attraction.<\/li>\n<li><strong>Giant covalent structure:<\/strong>\u00a0Atoms, strong covalent bonds throughout a network.<\/li>\n<li><strong>Simple molecular substances:<\/strong>\u00a0Molecules, weak <strong>intermolecular forces<\/strong>.<\/li>\n<\/ul>\n<p>Students lose marks when they describe an ionic solid as \u201cmolecules,\u201d or when they say covalent bonds are weak in a giant structure.<\/p>\n<h3><strong>The bonding-to-property table examiners love<\/strong><\/h3>\n<table>\n<tbody>\n<tr>\n<th colspan=\"1\" rowspan=\"1\"><strong>Substance type<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>What holds it together<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Typical property<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Explanation core<\/strong><\/th>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Ionic lattice<\/td>\n<td colspan=\"1\" rowspan=\"1\">Electrostatic attraction between oppositely charged ions<\/td>\n<td colspan=\"1\" rowspan=\"1\">High melting point<\/td>\n<td colspan=\"1\" rowspan=\"1\">Large energy needed to overcome strong attractions<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Giant covalent (diamond\/SiO\u2082)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Covalent bonds throughout<\/td>\n<td colspan=\"1\" rowspan=\"1\">Very high melting point<\/td>\n<td colspan=\"1\" rowspan=\"1\">Many strong covalent bonds must be broken<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Simple molecular (iodine, CO\u2082)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Intermolecular forces between molecules<\/td>\n<td colspan=\"1\" rowspan=\"1\">Low melting\/boiling point<\/td>\n<td colspan=\"1\" rowspan=\"1\">Less energy needed to overcome weak forces<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Metallic<\/td>\n<td colspan=\"1\" rowspan=\"1\">Positive ions + delocalised electrons<\/td>\n<td colspan=\"1\" rowspan=\"1\">Conducts electricity<\/td>\n<td colspan=\"1\" rowspan=\"1\">Delocalised electrons move through lattice<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Your explanation must specify whether energy breaks <strong>intermolecular forces<\/strong>\u00a0or <strong>covalent\/ionic bonds<\/strong>. That single distinction is often the difference between 1 mark and 3 marks.<\/p>\n<h3><strong>Intermolecular forces: <\/strong><strong>S<\/strong><strong>top calling them \u201cbonds\u201d in these answers<\/strong><\/h3>\n<p>From our direct experience with international school curricula, a frequent marker comment is \u201cconfuses bonds and forces.\u201d If you write \u201ccovalent bonds between molecules,\u201d you sabotage your own justification.<\/p>\n<p>A safer phrasing:<\/p>\n<ul>\n<li>\u201cStrong covalent bonds <strong>within<\/strong>\u00a0the molecule.\u201d<\/li>\n<li>\u201cWeak <strong>intermolecular forces<\/strong>\u00a0<strong>between<\/strong>\u00a0molecules.\u201d<\/li>\n<\/ul>\n<h3><strong>Conductivity explanations: <\/strong><strong>U<\/strong><strong>se electron language accurately<\/strong><\/h3>\n<p>The graphite vs diamond &#8220;explain&#8221; question is a classic because it tests precision.<\/p>\n<ul>\n<li>Graphite has delocalised electrons that can move and carry charge.<\/li>\n<li>Diamond uses all outer electrons in covalent bonds, so no mobile charge carriers.<\/li>\n<li>Therefore graphite conducts and diamond does not.<\/li>\n<\/ul>\n<p>Do not say \u201cgraphite has free ions.\u201d That is an ionic explanation, and it fails.<\/p>\n<h3><strong>Solubility and separation technique justification<\/strong><\/h3>\n<p>&#8220;Explain&#8221; questions\u00a0often ask you to justify a technique like filtration, crystallisation, or distillation. Your explanation should connect to particle behaviour and solubility, not just the name of the method.<\/p>\n<p>Example justification chain:<\/p>\n<ul>\n<li>\u201cThe insoluble solid remains as residue because its particles do not dissolve to form a solution.\u201d<\/li>\n<li>\u201cThe liquid passes through the filter because it contains only dissolved particles.\u201d<\/li>\n<li>\u201cCrystallisation works because solubility decreases on cooling, so particles form a solid lattice.\u201d<\/li>\n<\/ul>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/ultimate-igcse-study-plan-how-to-score-as\/\">Ultimate IGCSE Study Plan<\/a> 2026: How to Score A*s<\/p>\n<h2><strong>Explaining Trends In The Periodic Table Effectively<\/strong><\/h2>\n<p>Periodic trends are an explain-question goldmine because they force you to connect electron structure to macroscopic reactivity. Your answer must include the correct causal variable: Shielding, nuclear attraction, atomic radius, or electron gain\/loss tendency.<\/p>\n<h3><strong>Group trends: <\/strong><strong>W<\/strong><strong>rite them as cause-and-effect, not as facts<\/strong><\/h3>\n<p>A strong trend explanation has two components.<\/p>\n<ul>\n<li><strong>What changes down the group<\/strong><\/li>\n<li><strong>How that change affects reactivity<\/strong><\/li>\n<\/ul>\n<p>For Group 1 metals, you want this chain:<\/p>\n<ul>\n<li>Down the group, atoms have more electron shells, so atomic radius increases.<\/li>\n<li>Shielding increases, so nuclear attraction to the outer electron decreases.<\/li>\n<li>The outer electron is lost more easily.<\/li>\n<li>Reactivity increases.<\/li>\n<\/ul>\n<p>For Group 7 halogens, flip the logic for gaining an electron:<\/p>\n<ul>\n<li>Down the group, increased shells and shielding reduce attraction for an incoming electron.<\/li>\n<li>Electron gain becomes less favourable.<\/li>\n<li>Reactivity decreases.<\/li>\n<\/ul>\n<h3><strong>Period (across a period): <\/strong><strong>B<\/strong><strong>e selective and avoid dumping<\/strong><\/h3>\n<p>Across a period, you can mention increasing nuclear charge and decreasing atomic radius, but only if it links to what the question asks (reactivity, bonding type, oxides, metallic character). Examiners do not award marks for irrelevant trend narration.<\/p>\n<h3><strong>A diagnostic checklist for periodic &#8220;explain&#8221; questions<\/strong><\/h3>\n<p>Use this when you are stuck.<\/p>\n<ul>\n<li>Does the trend involve <strong>loss of electrons<\/strong>\u00a0(metals) or <strong>gain of electrons<\/strong>\u00a0(non-metals)?<\/li>\n<li>Which electron is involved: Outer shell, or an incoming electron?<\/li>\n<li>What is the dominant cause: Nuclear charge, shielding, radius?<\/li>\n<li>Can I end with a direct statement: \u201ctherefore it reacts more\/less because\u2026\u201d?<\/li>\n<\/ul>\n<h3><strong>Common misconceptions to remove early<\/strong><\/h3>\n<p>Based on our years of practical tutoring at Times Edu, these errors appear repeatedly in mock scripts.<\/p>\n<ul>\n<li>\u201cNuclear charge decreases down the group.\u201d It increases; effective attraction decreases because shielding and distance increase.<\/li>\n<li>\u201cAtoms want a full shell.\u201d Examiners prefer objective language: \u201cmore stable electron configuration\u201d supported by attraction\/energy arguments.<\/li>\n<li>\u201cReactivity equals electronegativity.\u201d They are related in some contexts but not interchangeable in explanation chains.<\/li>\n<\/ul>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-tutor\/\">IGCSE Tutor<\/a> 2026: How to Choose the Right One<\/p>\n<h2><strong>Constructing Logical Arguments For Chemical Equilibrium<\/strong><\/h2>\n<p>Equilibrium &#8220;explain&#8221; questions are scored for structure. You must define the dynamic nature, then apply <strong>justification<\/strong>\u00a0using collision\/particle logic and Le Chatelier-style directional reasoning.<\/p>\n<h3><strong>Start with the one sentence that anchors marks<\/strong><\/h3>\n<ul>\n<li>In a closed system, equilibrium is <strong>dynamic<\/strong>: Forward and reverse reactions continue at equal rates.<\/li>\n<\/ul>\n<p>That single sentence is often an explicit mark point.<\/p>\n<h3><strong>How to explain equilibrium shifts without hand-waving<\/strong><\/h3>\n<p>Use a three-step argument.<\/p>\n<ul>\n<li><strong>Disturbance:<\/strong>\u00a0What changed (concentration, temperature, pressure).<\/li>\n<li><strong>System response:<\/strong>\u00a0Which direction reduces the disturbance.<\/li>\n<li><strong>New equilibrium:<\/strong>\u00a0Forward\/reverse rates become equal again at a different composition.<\/li>\n<\/ul>\n<p>A critical detail most students overlook in the 2026 exam cycle is that Cambridge rewards \u201creasoned explanations\u201d as an explicit skill within AO2. Equilibrium questions are a direct test of that skill.<\/p>\n<h3><strong>Temperature changes: <\/strong><strong>T<\/strong><strong>reat exothermic and endothermic correctly<\/strong><\/h3>\n<p>A reliable method:<\/p>\n<ul>\n<li>If forward reaction is exothermic, heat is a product.<\/li>\n<li>Increasing temperature adds \u201cheat,\u201d so equilibrium shifts to consume it (reverse direction).<\/li>\n<li>Decreasing temperature shifts to produce heat (forward direction).<\/li>\n<\/ul>\n<p>Avoid the misconception: \u201cequilibrium moves to the side with more moles\u201d for temperature. That rule belongs to pressure changes for gases, and even then it must be justified properly.<\/p>\n<h3><strong>Pressure changes: <\/strong><strong>O<\/strong><strong>nly for gaseous equilibria, and only if moles differ<\/strong><\/h3>\n<p>Your justification must include:<\/p>\n<ul>\n<li>Pressure increase favours the side with fewer gas molecules because it reduces pressure.<\/li>\n<li>Pressure decrease favours the side with more gas molecules.<\/li>\n<\/ul>\n<p>If both sides have equal gas moles, state \u201cno change,\u201d and you often secure an easy mark.<\/p>\n<h3><strong>Equilibrium: <\/strong><strong>A<\/strong><strong>\u00a0short table that prevents common errors<\/strong><\/h3>\n<table>\n<tbody>\n<tr>\n<th colspan=\"1\" rowspan=\"1\"><strong>Change<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Correct direction logic<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Typical wrong answer<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Fix phrase<\/strong><\/th>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Add reactant<\/td>\n<td colspan=\"1\" rowspan=\"1\">Shifts to products to reduce reactant concentration<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cRate increases so more products form\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cThe system opposes change by consuming added reactants.\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Increase temperature<\/td>\n<td colspan=\"1\" rowspan=\"1\">Favours endothermic direction<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cAlways shifts right\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cHeat acts like a reactant\/product depending on \u0394H.\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Increase pressure<\/td>\n<td colspan=\"1\" rowspan=\"1\">Favours fewer gas moles<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cFavours more moles\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cShift reduces total gas molecules to lower pressure.\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Add catalyst<\/td>\n<td colspan=\"1\" rowspan=\"1\">No shift; speeds both directions equally<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cMoves to products faster\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cCatalyst does not change equilibrium position.\u201d<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-biology-explain-questions\/\">IGCSE Biology Explain Questions:<\/a> How to Write Clear, Effective Answers in Exams in 2026<\/p>\n<h2><strong>Frequently Asked Questions<\/strong><\/h2>\n<div class=\"hoi-dap-thok-new low-faq\">\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>How do I answer 6-mark &amp;quot;explain&amp;quot; questions in Chemistry?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">A 6-mark &#8220;explain&#8221; question is a structured argument, so plan it as 3\u20134 linked points before you write. Use the chain: Concept \u2192 particle mechanism \u2192 justification, and make each point a separate sentence so the examiner can award marks cleanly. Finish by directly answering the question wording to avoid \u201cgood science, wrong target.\u201d<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>What is the difference between &amp;quot;describe&amp;quot; and &amp;quot;explain&amp;quot; in Chemistry?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">Cambridge defines <strong>Describe<\/strong>\u00a0as stating characteristics\/features, while <strong>Explain<\/strong>\u00a0requires reasons, relationships, and supporting evidence. If your sentence does not contain a mechanism (particles, forces, electrons, energy), it is usually only a description.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>How to explain the effect of a catalyst on reaction rate?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">State that the catalyst provides an alternative pathway with lower activation energy. Then justify that a larger fraction of collisions are successful, so rate increases, while the catalyst remains chemically unchanged overall. Keep it specific: Activation energy and successful collisions are the key marks.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>What keywords are needed to explain ionic bonding?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">Use \u201cions,\u201d \u201clattice,\u201d and \u201celectrostatic attraction between oppositely charged ions.\u201d Add \u201cstrong attraction\u201d and \u201clarge energy required to overcome\u201d when explaining melting\/boiling points. Avoid \u201cmolecules\u201d in ionic explanations because it weakens scientific terminology.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>How do I justify the choice of a separation technique?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">Justification must cite the property difference: Solubility, boiling point, particle size, or miscibility. State the property difference, explain how the apparatus exploits it, and link to the outcome (residue\/filtrate, distillate, crystals). A short property-based justification usually scores higher than a long procedural story.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>Should I use diagrams when explaining chemical processes?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">Use diagrams when they replace 2\u20133 sentences of particle description, such as diffusion, electrolysis ion movement, or energy profile sketches. Label clearly with scientific terminology (ions, electrons, anode\/cathode), and do not rely on the diagram alone. If you add a diagram, still write at least one sentence explaining what it proves.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>How to explain equilibrium shifts using Le Chatelier&amp;#39;s principle?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">\n<p>State the disturbance, then write the system\u2019s response that reduces the disturbance, then state the new equilibrium outcome. Anchor your explanation with \u201cdynamic equilibrium\u201d and keep direction logic tied to the variable changed (temperature, pressure, concentration).If temperature changes, explicitly reference exothermic\/endothermic direction so the justification is unambiguous.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<p><strong>Conclusion<\/strong><\/p>\n<p>Based on our years of practical tutoring at <a href=\"https:\/\/times.edu.vn\/en\/\">Times Edu<\/a>, the fastest improvement comes from diagnosing which link\u00a0you usually miss: Concept selection, particle mechanism, or justification phrasing.<\/p>\n<p>When we build a personalised revision roadmap, we map your past-paper errors to the syllabus assessment objectives and then drill the exact explain-question patterns that are costing you marks.<\/p>\n<p>If you want Times Edu to design a personalized IGCSE Chemistry plan (topic sequence, explain-question drills, and timed paper strategy aligned to your school\u2019s pathway), share your target grade and your most recent mock-paper breakdown, and we will recommend the most efficient route to improvement.<\/p>\n\n\n<div class=\"kk-star-ratings kksr-auto kksr-align-right kksr-valign-bottom\"\n    data-payload='{&quot;align&quot;:&quot;right&quot;,&quot;id&quot;:&quot;35015&quot;,&quot;slug&quot;:&quot;default&quot;,&quot;valign&quot;:&quot;bottom&quot;,&quot;ignore&quot;:&quot;&quot;,&quot;reference&quot;:&quot;auto&quot;,&quot;class&quot;:&quot;&quot;,&quot;count&quot;:&quot;3&quot;,&quot;legendonly&quot;:&quot;&quot;,&quot;readonly&quot;:&quot;&quot;,&quot;score&quot;:&quot;4.7&quot;,&quot;starsonly&quot;:&quot;&quot;,&quot;best&quot;:&quot;5&quot;,&quot;gap&quot;:&quot;5&quot;,&quot;greet&quot;:&quot;\u0110\u00e1nh gi\u00e1 b\u00e0i vi\u1ebft&quot;,&quot;legend&quot;:&quot;4.7\\\/5 - (3 votes)&quot;,&quot;size&quot;:&quot;24&quot;,&quot;title&quot;:&quot;IGCSE Chemistry \\u0026quot;Explain\\u0026quot; Questions 2026: How to Write Clear, High-Scoring Answers&quot;,&quot;width&quot;:&quot;133.8&quot;,&quot;_legend&quot;:&quot;{score}\\\/{best} - ({count} {votes})&quot;,&quot;font_factor&quot;:&quot;1.25&quot;}'>\n            \n<div class=\"kksr-stars\">\n    \n<div class=\"kksr-stars-inactive\">\n            <div class=\"kksr-star\" data-star=\"1\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"2\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"3\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"4\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"5\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n    \n<div class=\"kksr-stars-active\" style=\"width: 133.8px;\">\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n                \n\n<div class=\"kksr-legend\" style=\"font-size: 19.2px;\">\n            4.7\/5 - (3 votes)    <\/div>\n    <\/div>\n","protected":false},"excerpt":{"rendered":"<p>IGCSE\u00a0Chemistry &#8220;explain&#8221; questions\u00a0are best answered by showing clear chemical reasoning: State the key concept, describe the particle-level mechanism, then justify the observable result using precise scientific terminology. High-scoring responses consistently link kinetic theory\u00a0and collision theory\u00a0to reaction rates, connect molecular structure\u00a0and intermolecular forces\u00a0to properties, and explain periodic trends through shielding and nuclear attraction. For multi-mark items, &#8230; <a title=\"IGCSE Chemistry &#8220;Explain&#8221; Questions 2026: How to Write Clear, High-Scoring Answers\" class=\"read-more\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-chemistry-explain-questions\/\" aria-label=\"Read more about IGCSE Chemistry &#8220;Explain&#8221; Questions 2026: How to Write Clear, High-Scoring Answers\">Read more<\/a><\/p>\n","protected":false},"author":7,"featured_media":35016,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"content-type":"","rank_math_title":"","rank_math_description":"","footnotes":""},"categories":[166],"tags":[],"class_list":["post-35015","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-igcse"],"_links":{"self":[{"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/posts\/35015","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/comments?post=35015"}],"version-history":[{"count":5,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/posts\/35015\/revisions"}],"predecessor-version":[{"id":36943,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/posts\/35015\/revisions\/36943"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/media\/35016"}],"wp:attachment":[{"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/media?parent=35015"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/categories?post=35015"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/tags?post=35015"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}