STUDENT SPACE · TOPIC 2

Collisions and exposed particles

Explain concentration, gas pressure and surface area using collisions.

The essentials

Key vocabulary

EnglishChinese
collision碰撞
concentration浓度
surface area表面积
successful collision有效碰撞

Quick practice

Try each question before opening its hint or answer. Use paper for calculations and diagrams.

Question 1

Does crushing 2 g of marble create more particles in total? Explain the rate change.

Need a hint for Question 1?

Build the explanation from number per volume or exposed surface to collision frequency.

Check Question 1

No. It exposes more surface particles, so successful collisions at the solid surface occur more frequently.

Question 2

Explain why increasing acid concentration increases rate at the same temperature.

Need a hint for Question 2?

Consider the number of reacting particles per unit volume.

Check Question 2

More reactant particles per unit volume cause more frequent successful collisions.

Question 3

A gas mixture is compressed at constant temperature. Explain why it reacts faster.

Need a hint for Question 3?

At constant temperature, focus on collision frequency rather than energy.

Check Question 3

Particles are closer together, so collisions and successful collisions occur more frequently.

Use Lesson 2 in your worksheet for written practice. Your teacher will discuss those answers in class.

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