Edexcel IGCSE Chemistry Topic 3.15 — Rates of Reaction is one of the most practical and experiment-heavy topics in the syllabus. Whether you’re measuring gas production with a syringe or investigating how surface area and concentration affect reaction speed, mastering this topic gives you a solid foundation for A-Level and beyond. This set of 23 flashcards covers everything from the core equation (CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O) to experimental technique and data analysis.
Edexcel IGCSE 化学 Topic 3.15 — 反应速率 是整个大纲中实验性最强的主题之一。无论你是用气体注射器测量气体产量，还是探究表面积和浓度如何影响反应速度，掌握这一主题将为你的 A-Level 及更高层次的学习打下坚实基础。这套 23 张闪卡涵盖了从核心方程式到实验技巧和数据分析的全部内容。
Key Knowledge Points / 核心知识点
1. Measuring Reaction Rate / 测量反应速率
Three common methods: (a) Gas syringe — measure volume of gas produced over time; (b) Mass loss — place the reaction vessel on a balance and record mass decrease as CO₂ escapes; (c) Upside-down measuring cylinder — collect gas over water and read the volume at regular intervals. Rate = total volume ÷ time.
三种常用方法：(a) 气体注射器 — 测量随时间产生的气体体积；(b) 质量损失法 — 将反应容器放在天平上，记录 CO₂ 逸出导致的质量减少；(c) 倒置量筒排水集气法 — 用排水法收集气体，定时读取体积。速率 = 总体积 ÷ 时间。
2. Surface Area Effects / 表面积的影响
Crushing marble chips into powder increases surface area, exposing more CaCO₃ particles to HCl at once. This leads to more frequent successful collisions per unit time — a faster rate. The same mass of marble produces the same total volume of CO₂ regardless of particle size; only the speed changes.
将大理石碎块研磨成粉末可 增大表面积，使更多 CaCO₃ 颗粒同时接触 HCl，导致单位时间内 成功碰撞频率增加 — 反应速率更快。相同质量的大理石无论颗粒大小都会产生相同总体积的 CO₂，改变的只是速度。
3. Concentration Effects / 浓度的影响
Higher HCl concentration = more H⁺ ions per unit volume = more frequent collisions between H⁺ and CaCO₃. To decrease concentration, add a known volume of deionised water to dilute the acid. Remember: this is a fair test — only one variable should change at a time.
HCl 浓度越高 = 单位体积内 H⁺ 离子越多 = H⁺ 与 CaCO₃ 之间的 碰撞更频繁。要降低浓度，可加入已知体积的去离子水稀释酸液。记住：这是公平实验 — 每次只应改变一个变量。
4. The Core Equation / 核心方程式
CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + CO₂(g) + H₂O(l) — This balanced equation tells you that 1 mole of marble reacts with 2 moles of HCl to produce 1 mole each of calcium chloride, carbon dioxide, and water. The CO₂ is the gas you collect to track progress.
CaCO₃(固) + 2HCl(溶液) → CaCl₂(溶液) + CO₂(气) + H₂O(液) — 这个配平方程式告诉你，1 摩尔大理石与 2 摩尔 HCl 反应，生成各 1 摩尔的氯化钙、二氧化碳和水。你收集的 CO₂ 就是用来追踪反应进程的气体。
5. Practical Tips for the Lab / 实验技巧
Always attach the bung immediately after adding reactants to minimise gas escape. Use a capillary tube to connect the flask to the gas syringe for smooth gas flow. Take readings at regular time intervals (e.g., every 10 seconds) and plot a graph of volume vs. time — the steeper the initial gradient, the faster the rate.
加入反应物后必须 立即塞上橡皮塞，以最小化气体逸出。用毛细管连接烧瓶和气体注射器，确保气体平稳流动。定时记录读数（如每 10 秒一次），并绘制体积-时间图 — 初始梯度越陡，速率越快。
Study Tips / 学习建议
- Active recall with flashcards: Cover the answer side and try to recall the full explanation before flipping. The 23 flashcards in this set are designed for rapid-fire revision.
- Draw the apparatus: Sketch the gas syringe setup and label each part — conical flask, bung, capillary tube, gas syringe. Visual memory aids recall in exams.
- Practice graph interpretation: Edexcel frequently asks you to interpret rate graphs. Practice drawing tangent lines at t=0 to find initial rates.
- Link to collision theory: Every rate question ultimately traces back to particle collision frequency and energy. Always frame your answer in those terms.
- 闪卡主动回忆：遮住答案面，尝试在翻面之前完整回忆解释内容。本套 23 张闪卡专为快速冲刺复习设计。
- 画实验装置图：绘制气体注射器装置图并标注各部分 — 锥形瓶、橡皮塞、毛细管、气体注射器。视觉记忆有助于考试时的信息提取。
- 练习图表解读：Edexcel 经常要求解读速率图表。练习在 t=0 处画切线以确定初始速率。
- 联系碰撞理论：每道速率题最终都追溯到粒子碰撞频率和能量。始终用这些术语组织你的答案。
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