I am going to investigate the concentration on the rate of reaction. For substances that may react, two things are necessary before they will react. For reactions involving more than one substance, the particles must collide before any reaction is possible. Not all collisions result in a reaction. Particles must collide with a certain minimum amount of energy, called the activation energy, before a reaction can happen. Molecules with low kinetic energy will probably just bounce off each other when they collide; molecules with high kinetic energy are more likely to have sufficient energy to break bonds and react.
1. Concentration – higher the concentration, faster the rate of reaction, because higher the concentration there are more particles in the solution, so there are more collisions. 2. Temperature – higher the temperature, faster the rate of reaction, because higher the temperature, the particles have more energy to move faster to collide more faster. 3. Surface Area – bigger the surface area, faster the rate of reaction, because bigger the surface area, there are more exposed on the particles for collision. 4.
Air pressure – higher the air pressure, faster the rate of reaction, because higher the air pressure, the volume of the solution will smaller, but the number of particles hasn’t change, the concentration increase, so the rate of reaction will increase. 5. Catalyst – it increase the rate of reaction because it provide a reaction pathway whose activation energy is lower. So there is more particles have energy to react when they collide – so the rate is faster. To avoid my results are not change by these variables, which may affect my investigation I will do the followings: 1.
Concentration – concentration of hydrochloric acid were already set up, so it is very less chance that the concentration are different from what is said. 2. Temperature – the temperature in the room need to keep constant, which it is usually do. 3. Surface Area – we will use regular marble chips so they will approximately the same size of surface area. 4. Air Pressure – the pressure in the air will not change in the sudden, so it won’t be a problem. 5. Catalyst – they are specific to a given reaction – they are not interchangeable, and in our experiment, we didn’t use a catalyst.
Prediction The shape of my graph will properly have a very steep slope first then getting gentler and gentler. This is because the reaction will start quickly of it is the time have the most collision at the start, but later, because there will be less particles to be collide, because most of them will use up, the reaction rate will start to slow down. I think when the concentration of the solution increase, the rate of reaction increases. This is because higher the concentration there is more particles in the solution, so there are more collisions with the others.
Quantitatively, when the concentration of the acid go up 2 times, the gradient will go up 2 times. This is because when there is 2 times the concentration, this means there will be twice as much particles for the reaction. So it can have twice the amount of collision with the others so it will produce twice as much the product it have. Preliminary Experiment The preliminary experiment need to carry out because I need to chose the mass of marble chips, and the amount of hydrochloric acid that we use to show a very quick reaction and have a good difference each time.
I am going to change the amount of marble chips – 0.50g, 1. 00g, 1. 50g and 2. 00g. And I am going to use the highest concentration of hydrochloric acid because I want to see which mass of the marble chips will not break through the gas syringe limit – 100. 0cmi?? which we cannot measure it. So the mass of this will not be a good mass to use. I am going to chose the one result that will show out when it increase very quickly at the start and have increase slowly at the end and eventually stop reacting, and I need a result that can show it all, or most of it, so I carry out the experiment like this: P. S. Do this experiment for the 4 different masses of the marble chips.
1. I measure the weight of the marble chips that I need on a mass balance. 2. I measure the volume of 20cmi?? of hydrochloric acid for my experiment which I will do the same each time 3. I set the apparatus like this: 4. Put the dilute hydrochloric acid into the flask while press the stopwatch. 5. Put the top on and give it a standard shake – shake it twice in clockwise direction, to make the reaction going on. 6. Measure the reading in the gas syringe every 10 seconds and do it 10 times. 7. Put the results into the table. And I got the result like this: The result of the experiment Concentration=2mol/dmi??
I will chose the 2. 00g one because it has a very different range of speed which change very quickly. Although it have gone through 100 cmi?? , the limit of the syringe, I will take out another experiment, which make the 2.00g marble chips constant and start the change the volume of the hydrochloric acid. I am going to do the same experiment but I measure the marble chips in 2. 00g all the time and I am going to measure the hydrochloric acid in 5 different variables – 5 cmi?? , 10 cmi?? , 15cmi?? and 20 cmi?? and I go the result like this: The result of the experiment Concentration=2mol/dmi?? Time taken (seconds)
I will chose the 10 cmi?? because it haven’t went out of the limit of the syringe even I use the highest concentration and the result change increase very quickly so I will chose 2. 00g of marble chips, 10 cmi?? of HCL concentration of 0. 25 mol/dmi?? , 0. 5 mol/dmi?? , 1 mol/dmi?? , and 2 mol/dmi?? and I will repeat my experiment 3 times for each concentration so I can do my average for my main experiment so I can find out is the quantitative relationship that I predict is right.
But because I want to find out the relationship between these different concentrations more clearly, Obtaining Main Method Safety precautions – HYDROCHLORIC ACID is CORRSIVE – Wear SAFETY GOOGLES I am going to do the followings: 1. I measure the weight of the marble chips of 2. 00g that I need on a mass balance. 2. for my experiment in the measuring cylinder which I will do the same each time. 3. I put the marble chips into the flask. 4. I set the apparatus like this: 5. Put the dilute hydrochloric acid into the flask while press the stopwatch. 6.
Put the lid on and give it a standard shake – shake it twice in clockwise direction, to make the reaction going on. 7. Measure the reading in the gas syringe every 10 seconds and do it 10 times. 8. Repeat the same concentration for 3 times. 9. Get the average of three results of that time to a next column. 10. Put the results into the table. To make it accurate, I will do a standard shake because this will make the reaction going on at the start. And the lid of the flask may leak some gas out, so I need to press it harder to avoid it. The result of the Main Experiment This shown as an anomalous result so will not include it.
Concentration=2. 0mole/dmi?? Analysis Fig. 1 Fig. 2 In this two graphs on fig. 1, which is the three experiments I have did for my concentration 0. 25mole/dmi??. And the fig. 2 is the gradient of both three averages. The gradient is found by taking two points on the line and, moving left to right from one point to the other, evaluating the fraction: distance moved up/ distance moved across. On this graph it show the gradient of this graph is 4. 8/10 cmi?? /s, which is 0. 48 cmi?? /s, which is very low. Fig. 1.