Rates of Reaction: Collision Theory, Factors and Measurement | 反应速率：碰撞理论、影响因素与测量

📚 Rates of Reaction: Collision Theory, Factors and Measurement | 反应速率：碰撞理论、影响因素与测量

In chemistry, the rate of reaction tells us how quickly reactants are converted into products. This topic is central to the Edexcel IGCSE Science course because it brings together the particle model, energy changes and practical measurement skills. In this article, you will learn the definition of rate, the collision theory, the four main factors that change reaction rate, and how to calculate rate from experimental graphs.

在化学中，反应速率告诉我们反应物转变成产物的快慢。该课题是 Edexcel IGCSE 科学课程的核心内容，因为它把粒子模型、能量变化和实验测量技能联系在一起。在本文中，你将学习速率的定义、碰撞理论、改变反应速率的四大主要因素，以及如何从实验图像计算速率。

1. What Is Reaction Rate? | 什么是反应速率？

Reaction rate describes the change in the quantity of a reactant or product per unit of time. In the laboratory, we can follow a reaction by measuring the volume of gas released, the loss of mass, a colour change or a change in pH. The formal definition is given by the equation below.

反应速率描述的是单位时间内反应物或产物数量的变化。在实验室中，我们可以通过测定放出气体的体积、质量的损失、颜色变化或 pH 值变化来跟踪反应。速率的正式定义如下式所示。

Rate of reaction = change in quantity ÷ time taken

反应速率 = 数量变化 ÷ 所用时间

Common units of rate include g/s for mass loss, cm³/s for gas volume, and mol/(dm³·s) for concentration change. For example, if 30 cm³ of hydrogen gas is collected in 20 seconds, the mean rate is 30 ÷ 20 = 1.5 cm³/s. Always include the unit in your final answer.

速率的常用单位包括：g/s（质量损失）、cm³/s（气体体积）以及 mol/(dm³·s)（浓度变化）。例如，若在 20 秒内收集到 30 cm³ 氢气，则平均速率为 30 ÷ 20 = 1.5 cm³/s。最终答案中一定要写明单位。

2. Collision Theory | 碰撞理论

For a reaction to happen, reactant particles must collide with one another. However, not every collision produces a reaction. A successful collision requires two conditions: the particles must collide with at least the activation energy, and they must hit each other

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