How does catalyst speed up a reaction

The two molecules will only react if they have enough energy. By heating the mixture, you are raising the energy levels of the molecules involved in the reaction. Increasing temperature also means the molecules are moving around faster and will therefore "bump" into each other more often.

More collisions afford more opportunities for reaction. How do catalysts affect the rate of a reaction? Catalysts speed up chemical reactions.

Only very minute quantities of the catalyst are required to produce a dramatic change in the rate of the reaction. This is really because the reaction proceeds by a different pathway when the catalyst is present essentially lowering the activation energy required for the reaction to take place. How does concentration affect the rate of a reaction? Increasing the concentration of the reactants will increase the frequency of collisions between the two reactants.

When collisions occur, they do not always result in a reaction atoms misaligned or insufficient energy, etc. Higher concentrations mean more collisions and more opportunities for reaction. What affect does pressure have on the reaction between two gasses? You should already know that the atoms or molecules in a gas are very spread out. For the two chemicals to react, there must be collisions between their molecules.

By increasing the pressure, you squeeze the molecules together so you will increase the frequency of collisions between them. You can easily increase the pressure by simply reducing the volume of the reaction vessel the gases are in. How does surface area affect a chemical reaction?

If one of the reactants is a solid, the surface area of the solid will affect how fast the reaction goes. This is because the two types of molecule can only bump into each other at the liquid solid interface, i. When the reaction has finished, the mass of catalyst is the same as at the beginning. Several examples of catalyzed reactions and their respective catalysts are given below:. Collisions only result in a reaction if the particles collide with a certain minimum energy called the activation energy for the reaction.

The position of activation energy can be determined from a on a Maxwell-Boltzmann distribution:. Only those particles represented by the area to the right of the activation energy will react when they collide. The majority do not have enough energy, and will simply bounce apart. To increase the rate of a reaction, the number of successful collisions must be increased. One possible way of doing this is to provide an alternative way for the reaction to happen which has a lower activation energy.

In other words, to move the activation energy to the left on the graph:. Adding a catalyst has this effect on activation energy. Catalysts only affect the rate of reaction - they do not affect the yield of the reaction.

A catalysed reaction produces the same amount of product as an uncatalysed reaction but it produces the product at a faster rate. Different substances catalyse different reactions. The table describes three common catalysts. Notice that these catalysts are transition metals or compounds of transition metals. A catalyst provides an alternative reaction pathway that has a lower activation energy than the uncatalysed reaction.

This does not change the frequency of collisions. However, it does increase the frequency of successful collisions because a greater proportion of collisions now exceeds this lower activation energy.

The effect of a catalyst on the activation energy is shown on a chart called a reaction profile.