In solutions of higher concentration, particles are closer together. They have a greater chance of colliding. Because there are more collisions the reaction rate is greater.
How does temperature affect the rate of a chemical reaction?
When two chemicals react, their molecules have to collide with each other with sufficient energy for the reaction to take place. This is collision theory. The two molecules will only react if they have enough energy. By heating the mixture, you will raise the energy levels of the molecules involved in the reaction. Increasing temperature means the molecules move faster. This is kinetic theory.
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. Adding extra catalyst will make absolutely no difference.
There are two ways in which catalysts work. When two different molecules bump into each other, they might react to make new chemicals. We usually talk about "collisions" between molecules; it would be much simpler to say that the molecules bumped into each other. How fast a chemical reaction is depends upon how frequently the molecules collide. You have probably been told about the "kinetic theory" which is all about heat and how fast molecules move around. What catalysts are doing when they make a chemical reaction go faster is to increase the chance of molecules colliding.
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. So this is collision theory again. Kinetic theory is relevant. This is because the molecules in the reaction mixture have a range of energy levels. When collisions occur, they do not always result in a reaction. If the two colliding molecules have sufficient energy they will react.
I predict that the higher the concentration of acid will be the faster the reaction will go; therefore a higher temperature will be reached. Increasing the concentration of the reactants will increase the frequency of collisions between the two reactants. If we increase the rate of reaction we increase the temperature rise of the reaction; a faster reaction allows more collisions to take place during the same period of time, which means there is a greater chance of more successful reactions when collisions take place. This results in more successful collisions and therefore more energy is released faster, releasing more heat to the surrounding environment.
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.e. on the surface of the solid. So the larger the surface area of the solid, the faster the reaction will be.
Smaller particles have a bigger surface area than larger particle for the same mass of solid. There is a simple way to visualize this. Take a loaf of bread and cut it into slices. Each time you cut a new slice, you get an extra surface onto which you can spread butter and jam. The thinner you cut the slices, the more slices you get and so the more butter and jam you can put on them. This is "Bread and Butter Theory". By chewing your food you increase the surface area so that digestion can go faster.
What effect does insulating the experiment have on the rate of reaction?
Insulating the experiment prevents heat loss therefore it keeps more energy within the experiment having the same effect as raising the temperature of the experiment. At higher temperatures, particles are moving faster, so there are more collisions. Also (and more importantly), the collisions are more energetic. More collisions have an energy greater than the activation energy, so the reaction is faster.
