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What effects the rate of a reaction

Extracts from this document...

Introduction

Factors affecting the rate of a reaction Possible independent variables - these are the factors that could be changed: - Surface area: volume of the magnesium - Temperature - Time: How long the magnesium piece is left in - Concentration of solution - Mass of magnesium All of these factors would have some kind of effect on the rate of reaction: We would expect that if the temperature was increased, then the rate of the reaction would occur quicker. When a mixture of substances is heated, the particles move faster. Since the particles are moving faster, they will travel a greater distance in a given time and so will be involved in collisions. Also, because the particles are moving faster, a larger proportion of the collision will exceed the activation energy and so the rate of reaction increases. The greater the surface area, gives a greater area for collisions to take place. Therefore this also increases the rate of a reaction. How long the magnesium was left in the solution would also affect the experiment, as we would expect that with a longer duration, there would be more time for the reaction to occur. As time as the changing factor it would be very difficult to get an accurate measurement of the rate of reaction. I do believe that mass wouldn't be a good independent variable as it would be hard to increase the mass of the magnesium without increasing the volume. Therefore I believe mass would be better suited as the dependent variable. Chosen independent variable - this is the factor (input) that I will change: - Concentration of solution I hope to use this variable as it would give me a wide variety of results and will give me an interesting conclusion. Controlled variables - These are the variables that I will keep the same so they make no disparity to the overall experiment: - Volume of hydrochloric acid with magnesium pice - Surface area: volume of magnesium piece - Time: ...read more.

Middle

So now I will simply look at concentrations from 1m to 2m. But unlike my preliminary experiment I will look into more detailed concentration. I will now look at concentrations of 1.25m and 1.75 m to the addition of the ones I have already looked at. The results in my preliminarily experiment seem very unreliable and simple. I need to repeat the experiment with each concentration at least three times to get concise and appropriate results. With three results I can easily find anomalous results and have more accurate results in the form of the averages. I am also generally happy with my method and the equipment used. However my method should be more detailed and instructive. I should include safety rules again as this is very important. I should also have a more detailed equipment list. I should of also explained the amount of hydrochloric acid needed to be used. I also believe I should review key factors, fair test and my variables one more time. Key Factors There are a lot of key factors that participate in this particular experiment. Certain factors have to stay constant throughout the whole experiment because they will help us find will accurate results. The factors that have to stay the same are: - Use the same size/scale of magnesium metal - Use the same measurement/amount of hydrochloric acid - Time all your results according to identical time scale for all your results - Use the same equipment for all your results e.g. test tube, measuring cylinder etc - Try to have the same room temperature throughout the process of your experiment. The factors that need to be changed are: Independent Variables: Change the concentration of the Hydrochloric acid every time you use a new piece of magnesium for a new set of results. Other Key factors: Independent Variables: The values I will use are: - 25 ml of hydrochloric acid - The different concentrations of hydrochloric acid that will be used are: 1m, 1.25, 1.5m, 1.75m, 2m (Molarity = m). ...read more.

Conclusion

The results were consistent. If I did want to further increase the reliability of my results, I could have obviously taken more readings to find more averages; this would mean needing more time. It would also be extremely useful to have more group members so there would be awareness of what is actually happening to the magnesium piece and more attention to specific concentrations. I furthermore had to rely on small test tubes, which meant we had to rinse and dry each one out after each experiment. It would be useful next time to have the freedom of having more measuring cylinders. Having previously cut magnesium pieces out or to have a machine cut the potatoes out more accurately would've definitely increased the consistency.. Finally it would be beneficial to have an alternative method of drying the equipment so to minimise the risk of absorbing water from the equipment or leaving water on the surface of the work board. Drying with a cloth may have not dried it completely. If I wanted to extend my investigation there are a number of elements I could change such as using temperature as a variable that would be changed to see how hot or cold concentrations affect the rate of a reaction. Or we could use the size (surface area to volume ratio) as a changeable variable to see how that affects a reaction. One other factor that would be interesting to test would be how a different substance that is soluble to the solution affects the rate of reaction, we would presume that it would be extremely similar to that of the experiment held in this investigation, although there may be other factors involved. The experiment overall was extremely successful in that the practical was completed in time and I had acquired reliable and accurate results which is proved on my line graph. I took all the necessary precautions outlined in the risk assessment of my plan. Overall I can again succeeding outline that through the experiment I have accomplished my aim and fulfilled the entire investigation. Rates of Reaction Coursework 1 ...read more.

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