满分回答：Decreasing the particle size of the solid will increase the fraction of particles available for collision, increasing frequency of effective collision & hence the rate of reaction.
2. Concentration/Pressure of liquid & gaseous reactants
满分回答：Increasing the concentration of a reactant (or the pressure of a gaseous reactant) will increase the number of particles in a unit volume. This will increase the frequency of effective collisions & hence the rate of reaction.
3．Temperature
满分回答：
When the temperature(T) increases, the reactant particles gain kinetic energy(KE).
The frequency of collision increases and the fraction of particles possessing energy equal or greater than the activation energy increases.
This results in an increase in the frequency of effective collisions between time.
Hence, rate of reaction increases.
Note: “frequency of collision & particles with rate of reaction” is required.
03
答案：B
解析 👇这道题考察的是 Catalyst。
Catalyst 定义：
A catalyst is a substance that increases the rate of a chemical reaction without being chemically changed at the end of reaction.
Catalyst can make activation energy decreased.Maxwell-Boltzmann energy distribution curve. 满分回答：Adding a catalyst decreases the activation energy of a reaction. Hence, the fraction of particles possessing energy equal or greater than the activation energy increases. This results in an increase in the frequency of effective collisions between time.
04
答案：A
解析 👇首先，一定要记住，catalyst 只能改变 activation energy，不改变 enthalpy change。所以，enthalpy change 还是 z，而 activation energy 从原来的 y+z 变成 x+z。Using a Maxwell Boltzmann distribution curve, explain how increasing the temperature increases the rate of reaction.解析 👇综上所述，IB化学非常注重基础概念的熟练程度，主要体现在题目更长、数量更多、跨度更大、细节更多、计算量更大等方面。在备考过程中，一定要注意通过基础题目的练习，增强自身对基础概念的灵活应用。由于在整个考试过程中，不允许使用计算器，所以学生也要注意提升自己的计算能力。
