The rate of reaction is the speed in which a reaction takes place.
This can be measured by the rate in which a reactant is used up, or the rate a product is created. If a reaction has a low rate, it means that the particles are combining at a slow speed. If the rate is high, it means that the particles are coming together at a fast speed. For example, the rusting of iron through oxidation has a slow reaction rate that can take a very long time, but the combustion of cellulose within a fire has an incredibly fast reaction rate taking place in a fraction of a second. Chemical reactions can only take place if particles that are reactants collide with enough energy. The more often particles collide, and the larger the amount of collisions occurring with enough energy, the higher the rate of reaction.
There are a few factors that affect the rate of reaction: • Concentration - increasing the concentration increases the probability of collision of the reactants. The collision theory, the idea that as more collisions occur in a system there will be more combinations of particles bouncing into each other leading to a higher number of collisions in a system, meaning that more particle combinations can occur. The reaction will happen quicker and the rate of reaction will be higher. If the concentration is lower there is less substance in the solution resulting in fewer collisions and a lower rate of reaction.• Temperature - When the temperature is higher in a system it gives more energy to the particles, they bounce around more and successful collisions occur at a greater rate, a higher reaction rate. If the temperature drops, the rate of reaction does also, a lower reaction rate.
• Pressure - When you increase the pressure the rate of reaction decreases. The added pressure means that the particles have less space to move around in, meaning that they are more likely to collide successfully. The greater the density of particles increases the amount of collisions occurring. If the pressure within the solution becomes smaller, the particles can move around more freely so collisions don't happen as successfully, this lowers the rate of reaction.•Catalysts - If you add a catalyst to a solution the reaction rate increases by providing an alternative pathway with a lower activation energy.
For instants, Platinum catalyzes the combustion of oxygen with hydrogen at room temperature.• particle size - The smaller the particle size the greater the surface area leading to more successful collisions and a faster rate of reaction. what effect does concentration have on the rate of reaction?• Prediction I predict that the amount of successful collisions and the rate of reaction will increase if I use a higher concentration of hydrochloric acid, double the strength of the less concentrated acid, during the chemical reaction of magnesium and hydrochloric acid.
