What Affects the Rate of Reaction? :: Reaction Rates Energy Science Essays

What Affects the Rate of Reaction? Hypothesis To form a reaction the particles must collide in high speed. The faster the particles collide the more kinetic energy is produced. This produces a bigger reaction. There are five key variables that affect the rate of a reaction (in this case with a solid and a solution): * Change in temperature An increase in heat energy within the particles leads to more kinetic energy. Therefore there is more collision of particles and it increases the rate of the reaction. When we decrease the amount of heat energy, this will evidently slow down the reaction. For example we slow down the process of our food rotting by placing it in a fridge or a freezer. * Change in concentration The concentrations of acids are classed in molars, so 2m would quite a strong concentrated acid, 0.5m would be a very dilute weak acid and 1m would be in between the two. Also, the more concentrated the acid, the more particles it contains, so there is more of a chance for collisions. * Change of particle size Increasing the surface area of the particles would lead to more collision. We do this by making the particles smaller. For instance peeling a large potato would not take as long as peeling four small potatoes; this is because the smaller potatoes have a larger surface area for you to peel. * Pressure (for gases only) Increasing the pressure would bring particles closer together so there would be more of a chance for collision. * Catalyst A catalyst lowers the activation of energy required, consequently there being a faster reaction. The three variables we are choosing to show which effect the rate of reaction in our experiments are: * Particle size * Concentration * Temperature Pressure was inappropriate to use as a variable, because we were not using two gases and a catalyst was unsuitable to use for small tests like these. I think that the tests in changing the temperature will have the fastest times, as the hotter a solution is the more the particles will move and collide, thus the rate of carbon dioxide being produce will be faster. I also think that the large particles test will take the slowest amount of time because of the lack of surface area and the reverse will occur with the test with powered calcium carbonate. Plan We will be running a various number of experiments to prove what effects the rate of reaction with calcium carbonate (marble chips) and hydrochloric acid. The balanced equation for these reactants along with the products: Calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water 2 2 3 2