C2 Rates of Reaction

There are four things which affect the rate of reaction:

• Temperature
• Concentration (pressure in gases)
• Surface area
• Catalyst

The higher the temperature the more energy particles have so they will collide more often.

The higher the concentration (pressure in gases) the denser the population of particles, so collison will occur more frequently.

The larger the surface area of a reactant (smaller size) the larger the area for particles to collide with is - so collsion will occur more often.

A catalyst is a substance which speeds up a reaction without being changed or used up.  Catalysts increase the rate of reaction by giving reacting particles a surface to stick to thus increaing the number of successful collisions.

Collsion theory explains how the rate of reaction is affected by how often (successful) and how hard reacting particles collide. 

Catalysts are very important in industrial use, however there are advantages and disadvantages to using them.

Advantages:

• They save the maunfacturer money as reactions can occur at a lower temperature so less energy is required: so they are environmentally beneficial as well
• Money is also saved as the product doesn't need to be manufactured for as long to get the same quantity of product
• Catalysts are not used up in reactions so they can be re-used

Disadvantages:

• They are relatively expensive to purchase and often need to be cleaned and removed from a product 
• Different catalysts are used for different reactions so multiple catalysts may need to be purchased, which is costly
• Impurities can poison catalysts maing them usesless - so reactions must be kept clean to avoid poisoning catalysts