# The Effects of Concentration on Rates of Reaction

Plan: I am going to investigate the affects of concentration on rates of reaction. I will do this by investigating the affect that different concentrations of hydrochloric acid have on a certain amount of marble chips. I want to see how long it takes for a set amount of carbon dioxide to be given off once the acid starts reacting with the marble chips. For a chemical reaction to take place the reacting particles must: A) Collide with sufficient energy or force for a reaction to take place. B) Collide head on so the reaction can take place. For this experiment I will be using the following apparatus: 1 boiling tube 1 bung seal 1 delivery tube 1 clamp and clamp stand 1 balance 1 measuring cylinder 1 stopwatch The boiling tube will have an arm on it so that the delivery tube can carry carbon dioxide to the gas syringe. The clamp and clamp stand will help keep the gas syringe steady while it collects the gas. I will measure a set amount of marble chips on the balance and time the experiment with the stopwatch. Louise Hewitt -????? Equation: Calcium Carbonate + Hydrochloric Acid à Calcium Chloride + Water + Carbon Dioxide The Equation for this reaction is CaCo3 + 2HCL àCaCl2 + H20 + CO2 Fair Testing: To make this experiment a fair test I need to keep all the values that I do not need to investigate the same. The variables that may affect this experiment are: ? Size of marble chip ? The size of the marble chip will have an effect on the experiment because the larger the surface area, the more acid that will come in contact with the marble and will be able to react more. I did an experiment to see how the size of the marble chip affected the rate of reaction. These are the results. Small Marble Chip 14 Seconds Medium Marble Chip 25 Seconds Large Marble Chip 51 Seconds ? Concentration of Hydrochloric Acid ? The proportion of hydrochloric acid in the solution. ? Volume of Acid- The amount of hydrochloric acid that will react with the marble chips. ? Temperature- An increase in temperature will cause an increase in the rate of reaction as the particles gain kinetic energy and move faster. To make the experiment a fair test we will keep all the values that we are not investigating the same. ? Mass of marble chips- The mass of the chips is a way of keeping the surface area the same. ? Temperature- Temperature effects how quickly the particles move as it adds energy to the reaction, increasing the number of collisions. By carrying out the experiment in the same lesson I hope that the room temperature will stay the same fairly constant. Louise Hewitt -????? Collision Theory: More particles react when there is more energy. If there are more molecules in the same place more reactions will take place. Prediction: === My prediction is that the higher the concentration, the faster the reaction will take place. This is because the more concentrated hydrochloric acid will have more molecules, so there will be more chance of the calcium carbonate ions colliding and reacting with the hydrochloric acid. ================ Evaluation: I think that my experiment worked well, as my results on my graph do appear to be accurate and they agree with my hypothesis. While conducting my experiment my results were all similar, and after I had repeated the anomalies they all fitted in with each other, which was very encouraging. Although I am happy with the quality of my results there are ways in which my experiment could have been more accurate. There was no way I could have made sure the room temperature had stayed the same during my experiment, so to make the test more accurate I could have done carried out my testing in a temperature controlled environment.

The Effects of Concentration on Rates of Reaction 7.2 of 10 on the basis of 2005 Review.