Question

Copper oxide reacts much faster with acid at 40°C than at 20°C. Why is this?

Explain in terms of particles.

Answer 1

It is due to a principle within chemical kinetics called collision theory

Explanation:

Collision theory states, that for particles to react, they have to collide in the correct orientation and have sufficient energy to create a successful (reacting) collision.

Take a simple Maxwell-Boltzmann distribution curve (this curve shows the number of particles in a system with a certain energy):

At the initial temperature ( `T1=20°C` ), only particles enclosed within the activation energy (Ea) and between T1 and the x-axis had sufficient energy to react. I.e. only particles within the dark green area could react.

Once the temperature was increased to `T2=40°C`, more particles had enough energy to react, as the number of particles with enough energy increased from the dark green area to the dark and light green area.

In simple terms: "As the temperature of a system is increased, more particles have sufficient energy to overcome the activation energy and perform a successful collision. Hence, more of the particles can readily react, increasing the rate of reaction at higher temperatures."