Speed of Reaction

Particle size of soilds

Zinc powder having a smaller particle size than zinc lumps has a larger total surface area for the reacting particles to collide with resulting in a more frequent collision and a more frequent effective collision and a faster speed of reaction

Concentration of solution

At a higher concentration, there more reacting particles per unit volume. Thus the reacting particles are closer together leading to a more frequent collision and a more frequent effective collision and a faster speed of reaction.

Pressure of gases

Gas pressure refers to the force exerted by gas particles when they collide with a surface. At a higher pressure, there are more reacting particles per unit volume and the reacting particles are closer together leading to a more frequent effective collision and a more frequent collision and a faster speed of reaction.

Temperature

At a higher temperature, the reacting molecules move faster and collide with more energy. Thus there will be more reacting particles with energy equal to or greater than the activation energy leading to more frequent effective collision and a faster speed of reaction.

Catalyst

Is a substance that is added to speed up the rate of reaction while it remains chemically unchanged and quantitavely unchanged at the end of the reaction.

How does a catalyst work?

A catalyst provide an alternative route with a lower activation energy for the reaction to occur, thus more reacting particles have energy equal or greater than the catalysed activation energy resulting in a more frequent effective collision and a faster speed of reaction