Essay Sample on The rate of reaction would increase
From my prediction I can conclude and make myself a set of hypothesis: 1) As the temperature increases as will the rate of reaction. 2) At all temperatures the same amount of gas will be formed 3) The temperature of the solution will increase as the reaction is taking place 4) If any of the other variables mentioned are changed it will affect the rate of reaction. To prove hypothesis number 4, I will attempt to do experiments in which I keep the temperature and change the other variables. This will also prove that they are variables and that I have not made a mistake by including them in my list of variables.
Another prediction which I can make concerns volumes, and the maximum amount of hydrogen which can be formed using the mass of magnesium and volume of Hydrochloric acid used. The mass of 80mm of magnesium is 0. 071g. First I have to find out the number of moles of magnesium. Moles of Mg used = Mass R. A. M = 0. 071g 24 = 2. 95×10-3 Because from the equation we can see that there is the same number of moles for Mg and H2, they both have 1 mole, the figure is the same for the moles of H2. 2. 95×10-3. 1 mole oh hydrogen takes up 24000cm3 in volume.
Therefore, 0.00295 will occupy: 24000 x 0. 00295 = 70. 8cm3 This means that no matter what the temperature, the maximum amount of hydrogen which can be formed from the reaction can be 70. 8 cm3 APPARATUS AND ITS SET UP The following apparatus will be needed for the experiment: Conical flask: this will contain the hydrochloric acid and the magnesium Gas syringe: this will be used to measure the amount of hydrogen produced Thermometer: to measure the temperature of the solution 50cm3 measuring cylinder. To measure the amount of acid, as accurately as possible.
Bung with hole: this will be used to stop any gas from escaping through the top of the conical flask. The hole is so I can insert a thermometer to measure the temperature of the solution inside. Water Bath: this is so I can heat the hydrochloric acid to the desired temperature and keep it constant throughout the experiment. If I used a Bunsen burner it would be impossible to keep the temperature constantly at a certain point. Rubber tubing: to connect the conical flask with the gas syringe Timer: to measure the elapsed time. Hydrochloric acid: 50cm3 for each experiment
Magnesium: 80mm for each experiment Goggles: as a safety precaution. Clamp stand: to hold the gas syringe in a constant position, therefore stopping any errors in the reading of it. The apparatus should be set up as shown on the other side of the paper. SAFETY AND FAIR TESTING Because of the nature of this experiment safety precautions must be taken. The use of goggles must be taken at all time, due to the corrosive nature and of the temperature of the acid. The utmost attention must be constantly paid towards the apparatus as a crack or leak in the conical flask might lead to very unwanted results.
As in all experiments the apparatus must be handled with care as any faulty equipment might be dangerous and might lead to a set of incorrect results. Keeping the experiment a fair test is a vital procedure, as this will give me reliable results. The most obvious variables that I must keep constant are the 5 mentioned in the scientific theory. The 6th, temperature, will obviously not be kept constant, as that is what I am investigating. The magnesium which I use is normally left in the air before I use it, and tends to have formed a layer of oxide, a black substance, around it.
I will use sand paper to remove the oxide. If the oxide is not removed it will be an unfair test, because the reaction will take longer, as the oxygen layer acts as a shield, and it will take a while before it dissolves, and magnesium and hydrochloric particles react. The other 5 and the ways in which I am going to keep them constant are: Concentration of hydrochloric acid: I will make sure that I use a constant molar of acid and to make sure that the conical flask is dry before putting any acid in as any water in the acid would lower the concentration.
Surface area: To keep this constant I must use the same strip of magnesium and keep it at the same length throughout the investigation. Volume of acid: will measure the volume of acid using precise measuring tools. There must also be no extra acid left in the conical flask between the interval of two experiments as this would lead to a false amount of acid in the flask. Catalyst: I will add no catalyst to the acid. Pressure: before each experiment I will open all the holes into the flask ensuring that the pressure level is kept the same.
A factor that is not included in the variables but that I will keep the same is the working condition in which the experiment will take place in. METHOD AND PROCEDURE The following procedure must be followed to ensure a reliable set of results: 1) Set up the apparatus as shown in the diagram on the previous page 2) Measure out 50cm3 of 0. 5m hydrochloric acid. I have chosen this amount as preliminary tests show this amount to be suitable to what I am doing. Any more acid would prove to be a problem, as too much hydrogen would be formed then 100cm3, the maximum range of the gas syringe.
3) Measure 8cm of magnesium. This measurement was also chosen from a preliminary experiment. Also one must sand off the black oxide which layers magnesium when it is left in air for too long. 4) Pour the hydrochloric acid into the conical flask. 5) Put the flask into the water bath and wait as the hydrochloric acid heats up to the appropriate temperature. 6) Add the magnesium to the acid close the bung and begin measuring the experiment 7) Using the gas syringe to measure the amount of gas produced every quarter of a minute. 8) Repeat this procedure at either a different temperature or the same one.
I will make measurements at the following temperatures: 10i?? C, 20i?? C, 30i?? C, 40i?? C, 50i?? C, and 60i?? C. I will repeat each temperature at least once and then find an average. I will measure 5 temperatures to see if there is any proportional relationship between any of my factors. My decisions on the range and on the number of readings that I will take have been premeditated from results of preliminary experiment. I found that using only 25cm3 of 1. 0M of acid and 5cm of magnesium was insufficient, as all the magnesium had reacted within 45 seconds.
This would be too small a time to see any change on a graph and comparison between thee graphs would be virtually impossible. I therefore, need to use a lower concentration of acid, as there will be fewer collisions, making the experiment react slower, giving me enough time to collect a suitable amount of data. And I will also change the amount of acid from 23cm3 to 50cm3 as this means that there are more particles to collide with, and the experiment may take longer. My choice for going up only to 60i?? C is due to the fact that after that point the hydrochloric acid begins to evaporate.
This was found during a preliminary experiment where after 50cm3 of hydrochloric acid was heated to 70i?? C only 45cm3remained when poured into a measuring cylinder. And if I do lose any acid before the experiment one of my variables, which is the volume of hydrochloric acid, will change and therefore lead to an unfair test. Another matter, which was uncovered during the preliminary testing, was that sometimes not all the magnesium was immersed into the acid at once as it was too long (i. e. it was stuck vertically to the flask and only a little bit was immersed at first). This gives drastic changes in the results.
Therefore, the magnesium must be coiled up before it is placed into the acids so that all of it is immersed. BIBLIOGRAPHY I have you the following sources to help for the planning of this report. Nigel D. Purchon PURCHON. COM Lawrie Ryan CHEMISTRY FOR YOU ANALYSIS WHAT I HAVE SEEN Looking at the results table the obvious connection with temperature and the rate of reaction is there, as the temperature increases so does the rate of reaction. So going back to my prediction I can say that I was accurate in the fact that I had predicted that as the temperature increases the rate of reaction also increases.
That evidence is clearly shown in the graph of the rate of reaction. Just to make things easier on the explanation I will create a list of things which the results show mw. This will make reference to each point easier. 1) The rate of reaction increased as the temperature increased. 2) The amount of hydrogen gas formed at the end of the experiment increases as the temperature increases, after my prediction stated that the number should be the same. Also after my prediction said that the total volume of hydrogen that could possibly be formed would be 70. 8cm3, three of my experiments were higher.
3) The reaction at the beginning of the 200C experiment was slower than the reaction at the beginning of the reaction for 100C. 4) The repeat of a temperature does not always match well with the first attempt. You can say that the rate of reaction will obviously be faster as the temperature increases because the total volume of gas formed will increase. This is not true because I am not measuring the rate of reaction through dividing the total volume of gas formed by the 300, the total time. But instead I am dividing the volume of gas formed by the time the gas took to reach its completion point.
For example, at 500C the total amount of gas formed may be 72. 00cm3, however it may have taken 300 seconds (5 minutes). And in an experiment where the temperature was only 300C may have produced only 59cm3 of gas but may have only taken 105 seconds. If we use my formula we find out that the rate of reaction for 500C is 0. 24 cm3/s, where as for 300C the rate of reaction is 0. 59cm3/s. So we see that actually the rat of reaction was actual quicker when the temperature is at 300C. However, this does not happen in my experiment and the rates of reaction increase as the temperature increases.
However, something which I had predicted does not represent itself in my results. My prediction was, that even though the rate of reaction would increase the final volume of gas collected would be the same for all temperatures. This would be because of what I explained earlier, that if the reaction took less time to accomplish the rate of reaction would be faster. Therefore, I have myself proved my prediction wrong. I was unable to prove my prediction that as the reaction takes place the temperature will increase as this is an exothermic reaction. This was due to an error in reading which could not be fixed.
My fourth prediction, that if you change any of the factors mentioned in the variables list you will get an unfair test, was not proven. This was due to problems with time. However, some of my colleagues did test the variables which I mentioned and they did get changes in the rates of reaction by increasing or decreasing the variable. WHAT THE GRAPHS SHOW US What I have explained before is all shown on the graph. What we need to understand is where and how it is like that The first thing that is to be explained about the graphs is how it shows us that the rate of reaction is faster.
It would be obvious, if someone was to be asked that question that they would look at the rate of reaction graph. However, if that information was not present, and if you did not know how to work out the rate of reaction the graph which shows the volumes of hydrogen produced is sufficient. What we know is that on the x axis we have the time, and on the y axis the amount of hydrogen formed. So the rate of reaction would be faster when the volume of gas formed is higher and the time taken to reach this, lower. This can be seen by the gradients of each curve.
The higher the gradient the higher the rate of reaction. So therefore from that graph, knowing the rate of reaction is quickest on the steepest gradient, you can find out that when the temperature was 60oC the reaction was fastest This happens because of both the collision/kinetic theory and because of activation energy. As the temperature of the hydrochloric acid increases the atoms inside move faster as they receive more energy from the extra heat provided. This means that the particles move faster, and they collide more often.