Investigating Rates of Reactions Essay Example for Free

Investigating Rates of Reactions Essay Investigate which factors out of temperature, surface area and concentration speed up the reaction between magnesium and hydrochloric acid the most. Chemical reaction: Mg (s)+ 2HCI (aq)== MgCI2 (aq)+H2 (g) Prediction: I think the most effective factor to speed up the rate of reaction will be temperature, I say this because when the molecules are at a higher temperature they will have greater kinetics energy and move more rapidly, so they will collide more frequently and most importantly with greater energy. Then surface area will be second greatest effect, increasing the surface area of the solid increases the number of collisions between solid and particles in solutions. If we take into consideration a cube with each side 1cm long it has a total surface area of 6cm2, halve each of the cubes so that there are eight cubes each with 0. 5cm long sides and the total surface area has doubled to 12cm, now halve the size of these smaller cubes. Surface area of 1 cube, sides 1cm= 6 sides x (1cm x1cm) = 6cm2 Surface area of 8 cubes sides 0. 5cm= 8 sides x 6 sides x (0. 5 x 0. 5)=12cm2 Surface area of 64 cubes, sides 0. 25cm= 64 cubes x 6 sides x (0. 25 x 0. 25)= 24cm2 Having the average size of the particles in a given quantity of solid, doubles the surface area. So making a solid reactant in a lump form into powder considerably increases the surface area. Concentration will be the third greatest factor, which will speed up the rate of reaction. Any increase in concentration should also increase the rate of reaction; if there are more molecules present there will be more collisions. Increasing the number of collisions does not always increase the rate of reaction. What matters is the numbers of effective, effective collisions have to involve the relevant molecules, in the correct orientation, with energy at the least equal to the activation level. Equipment   Conical flask   Hydrochloric acid of 4 different molars (0. 1, 0. 5, 1, 2) Stop clock Basin of water   Bung with the tube   Magnesium   Measuring tube   Top pan balance Plan: Concentration Four different concentrations will be used. (0. 1, 0. 5, 1, 2) firstly I will use the 0.1 molar of hydrochloric, 6cm of magnesium in conjunction with the 15 ml of hydrochloric acid. When the bung is put into the conical flask the amount of gas given off can be read. I will leave the magnesium and the acid for 1 minute and I will check how much gas is given off every 10 seconds and I will record it. This will be done for all the other ranges of concentrations. Temperature I will be using 4 different temperatures (fridge 12oC, room 24oC, 50oC, 60oC). The high temperature acids will be placed in a water of their designated temperature. The other acids will be placed in their obvious places. The acid will be put in the conical flask with 6 cm of magnesium then the gas given off will be read and recorded as done previously for the concentration. Surface Area For surface I will be using 5 different lengths of magnesium ribbon, (6, 5, 2, 1, 0. 5cm) I will also be using 0. 06g of magnesium powder. Each measurement of magnesium will be used in conjunction with 15ml of hydrochloric acid. When both elements are put into the conical flask the gas given off will be read and record in the same fashion as the other tests. For each test I will do it twice to make sure my results are realiable. Fair test To ensure that I carry out a fair test I will make sure I will use the same amount of magnesium apart from when I am testing that particular variable. Also I will also use the same amount of hydrochloric acid, also I will use the same concentration apart from when Im testing that variable. I will also time each test for the same amount of time. Safety   Safety goggles worn at all times.   Precautions taken when dealing with acids.   Follow all the rules of the lab so that I can work efficiently alongside others when they are doing their experiments. Results  Concentration 2nd set of results Temperature  Fridge 4 Conclusion From doing this investigation I have successfully achieved my aim, my aim was to investigate the factors, which affect the rate of reaction. My prediction was also correct. For concentration the gas given off for o. 1 molar of hydrochloric acid was much less that what was given off for 2 molar. When powder was used for surface area ample amounts of gas was given off where as when 6cm was used not much was given off. When the acid was at a higher temperature more gas was given off, this hypothesis wasnt backed up with the results from the first test, which is why it was good that I repeated all the tests. Evaluation On a whole I thought I worked quite well, but the investigation could have been conducted in a better fashion. The particular method we used to collect the gas wasnt that effective. If a gas syringe in conjunction with a clamp stand was used our results would have been much better. I think doing the investigation twice was a good decision because doing this made it manifest that the first set of results werent as reliable, this is because when the first set of results were compared to the 2nd set of results they were quite different especially room temperature and 50oC. In the experiment the amount of gas given off for those specific temperatures were lower than the second experiment. Scientific knowledge proves that when the temperature is raised the rate of reaction will be faster. Also another thing I could of done was to do all experiments in the method we did to collect gas and also kept everything the same but the variable to change could have been the method in which we collect the gas. By doing this I could of seen which method to collect the gas would have been most effective. Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour section.