The experiment will be on the reaction of Nitric acid and marble chips. CaCO3 + 2HNO3 Ca(NO3)2 + CO2 + H2O This particular reaction is rather slow and so needs to be quicker by changing the factors that affect the rate of reaction. In order to make predictions I need to research on what factors there are and from that, I will be able to draw up a prediction for the experiment. Introduction There are five ways that the rate of reaction can be affected 1. Temperature 2. Surface area 3. Pressure in gaseous reactions 4. Concentration 5. Catalyst This is why: Temperature: Surface area: Pressure: High Pressure Low Pressure.
Concentration: Catalyst: All of these factors have something to do with the collision theory. The rate of reaction depends on how often and how hard the reacting particles collide with each other. The basic idea is that particles have to collide in order to react, and they have to collide hard enough as well. All of the above methods of increasing the rate of reaction can be explained in terms of number of collisions, between reacting particles: 1. Temperature: when the temperature is increased the particles all move quicker. If they are moving quicker, they are going to have more collisions.
2. Concentration or pressure: If the solution is made more concentrated it means there are more particles of reactant knocking about between the water molecules which makes collisions between the important particles more likely. In a gas, increasing the pressure means the particles are more squashed up together so there will be more collisions 3. Size of solid particles (surface area) increases collisions: If one of the reactants is a solid then breaking it up into smaller pieces will increase its surface area. Thus there will be more area for the particles to work on hence more collisions 4.
Catalyst: This works by giving the reacting particles a surface to stick to where they can bump into each other. This obviously increases the number of collisions. Catalysts lower the activation energy of reactions, making it easier for them to happen. This means a lower temperature can be used. In addition, this helps reduce costs in industrial reactions. Faster collisions are only caused by increasing the temperature. Reactions only happen if the particles collide with enough energy to make the reaction happen. This initial energy is known as the activation energy, and is needed to break the initial bonds. Hypothesis and Prediction.
My prediction is that as you increase the temperature there will be an increase in the rate of production of CO2. Below is the graph that I will expect to get from my results: Volume Of CO2 Lost (cm3) Temp (? C) The graph for rate against temperature would look like this: Rate 1/T Temp (? C) In Graph 1, as you increase the temperature, there will be more particles with the activation energy thus causing more collisions. This would thus cause an increase in the rate of reaction. In Graph 2, as you increase the temperature the rate decreases. Plan Firstly, I plan to set out the experiment as shown in the diagram below.
I will then be doing three runs for five different temperatures. I will be doing 3 runs for each temperature to get a more accurate and precise result, the more runs the better but due to the amount of time given for the practical I will only be able to do 3 runs each. Once I have gained the results, I will put my results onto graphs and then work out the rate of reaction for each by using the formula: Difference in Y = Rate of Reaction Difference in X Where the difference in Y and X is found through triangulation, where only the steepest part of the line will be analysed.
I will then plot a final graph with the rate plotted against temperature to show more clearly the difference in the rate at different temperatures. Then finally I will analyse the final graph and show what I have found and I will see whether my prediction will be proved and then to evaluate the experiment and what I have found. Apparatus The following equipment is required for the experiment: Marble chips of a mass of approximately 0. 4g. 20ml of bench HNO3 for each run 1 Boiling tube 1 Stop-watch 1 Measuring Cylinder 1 Water bath filled with water 1 Bung 1 Stand 1 Bosses and 1 Clamps,1 Beaker.