Chemistry - Speed of Reactions

How do we know when a reaction has finished on a graph?

The line goes flat

How do you calculate the average rate of reaction?

change in quantity/change in time

Does a reaction happen faster when particles are larger or smaller?

Smaller

Why did the smaller particles react faster?

Because as the size decreases, the surface area increases

Why does more surface area mean a faster reaction?

Because there is more surface area for acid to react with

Does a reaction happen faster when the temperature is higher or lower?

Higher

Why does temperature effect reaction rate?

At higher temperatures particles move faster and therefore collide more frequently. The more collisions, the faster the reaction rate.

Does a reaction happen faster at a higher or lower concentration?

Higher

Why does a higher concentration effect the reaction rate?

At a higher concentration, there are more particles, therefore more collisions

What is a catalyst?

A substance that speeds up the rate of a chemical reaction

Does a catalyst change during the course of a reaction?

No

What is the name given to a biological catalyst?

An enzyme

What is a homogeneous catalyst?

A catalyst that is in the same state (solid, liquid or gas) as the reactants

What is a heterogeneous catalyst?

A catalyst in a different state (solid, liquid or gas) to the reactants

What are the four ways you can speed up a reaction?

- Decrease particle size
- Increase temperature
- Increase concentration
- Use a catalyst.