Investigating The Affect of Concentration on The Rate of Reaction Aim- To find out if changing the concentration of the hydrochloric acid affects the volume of gas released in 5 minutes. Background Information The rate of reaction depends on four things:- 1. Temperature 2. Concentration 3. Catalyst 4. Size of particles/surface area The Collision Theory The collision theory explains the rates of reaction, the rate of reaction depends on how often and how hard the reacting particles collide with each other.
The basic theory is that particles have to collide with each other in order to react, but it is not that simple, as it also depends on how hard the particles collide. If the particles do not collide hard enough then they will not react, they will simply just hit each other and ‘bounce’ off. This means that even if I am not investigating the rate of reaction when the temperature is changed, it will still have a big part to play in my experiment. If the temperature is different in the classroom when I do each concentration of acid it may have a huge impact on my results.
To help keep my results as accurate as possible I could take the temperature of the room before I do each experiment. If the temperature in the room is below 20 C the particles will still be moving, but very slowly. This would cause the react to be very slow. At temperatures above 20 C the particles will be moving at a regular speed. Low Concentration High Concentration Activation Energy Activation energy is the energy needed to start a reaction. Each molecule has a certain amount of energy, when molecules collide they have to collide with more energy than they already have in order to react this is called a successful collision.
If the molecules collide but do not create enough energy this is an unsuccessful collision and the molecules do not react. I am going to focus on the concentration. If the concentration of the hydrochloric acid is increased, then so will the number of collisions. If the acid is more concentrated it means that there will be more particles in the same size space compared to a diluted acid, this means collisions will be more likely and more frequent as the particles are closed together. Diagram of Equipment Apparatus I Will Need:- Conicle flask Glass syringe Bung Delivery tube.
Marble chips(5 grams) Hydrochloric acid(50 cm ) Stop clock Other Apparatus that I May Need:- Stand (to hold up gas syringe) * Thermometer (to take the temperature of the room before do each concentration. ) Weighing scales (to weigh out marble chips). Method I am going to change the concentration of the hydrochloric acid to test which concentration is the best. I am going to use the range of 0. 25M-2. 00M with 0. 5M, 1. 0M and 1. 5M in-between.
I will keep the surface area of the marble chips the same, ( to my best ability, I will keep them around the same size e.s used the same, the temperature of the marble chips, the acid and the room the same and the amount of hydrochloric acid used the same. I am going to measure the quantity/volume of gas released in five minutes. I will take a reading of how much gas has been released every thirty seconds, as I believe this will show the differences of gas released from start to finish between all concentrations. To Keep My Investigation Safe:- I will wear protective glasses incase any acid is splattered.
I will also wash my hands after I have touched the hydrochloric acid so that it does not irritate my skin and so I cannot rub it into my eyes. To Keep My Investigation Fair:- I will do all of the things that I said I will keep the same in my method. I will repeat the experiments three times and then work out an average, as I believe that this will give me accurate readings and point out an odd results e. g. if after 1 minute on the 0. 25M I got 2cm, 2. 2cm and 5cm then 5cm would be odd as the other two are close together, so I will not count the 5cm I will take the average from the other two results.
Prediction I predict that the 2. 0 molar acid will have the quickest reaction time and the 0. 25 molar will have the slowest reaction time I believe this because the stronger the concentration the more acid molecules there are, so there is a more likely chance of a collision compared to a weaker concentration of acid where there are less acid molecules therefore there is less chance of a collision. I believe that the other concentrations will go in order of highest concentration fastest time, lowest concentration slowest time.
So it will go(best-worst time) 1. 5, 1, 0.5( See collision theory for a more detailed explanation. ) Preliminary Results Results To Show The Amount of Gas Given Off In 5 Minutes Concentration Volume of gas produced(cm ) of acid(M) Time(minutes) My preliminary results show that 0. 5M will give the least amount of gas of in 5 minutes and 2M will give the most gas off in 5 minutes. These have given me an idea of what my results for my main experiment will be like.