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An investigation to find out what factors affect the rate of a reaction

Extracts from this document...

Introduction

October 2003 Chemistry coursework: An investigation to find out what factors affect the rate of a reaction The purpose of my investigation is to find out, which factors affect the rate of a reaction. I will then choose one factor to further investigate and experiment with, to observe how this factor affects the rate at which a reaction occurs in an experiment. The 'rate of reaction' is the speed or velocity at which a chemical reaction proceeds. We can't work out exactly the rate of a reaction through a chemical equation, but by actually conducting an experiment. All substances are made from particles, they can be ions, atoms, or molecules, to create a chemical reaction, and the particles must crash together. They must collide; this is the collision theory. It depends on how often and how hard the reacting particles collide with each other, as this is the basic idea that particles have to bump into each other to create a chemical reaction. There are five factors that affect and can alter the rate of a reaction, they are: * Surface area * Catalyst * Pressure * Temperature * Concentration Surface area In a reaction the surface area can affect a chemical reaction, if one of the reactants is a solid, the surface area of a solid will affect how fast a reaction proceeds. This is because, the two types of molecules can only bump into each other at liquid/solid interface i.e. on the surface area of the solid, so the larger the surface area of the solid, the faster the reaction will be. Smaller particles have a bigger surface area than larger particles for the same mass of solids. A simple way to visualise this is by taking a loaf of bread, and cut it into slices. Each time you cut a slice the surface area increases on to which you can spread butter. ...read more.

Middle

Preliminary To understand the investigation thoroughly and to clear what variables could affect the rate of the reaction, I conducted a preliminary experiment to make myself clear, and decide on how the actual experiment will be conducted. In my preliminary experiment I followed the appropriate method by using the correct amount of solution and heated it to an appropriate temperature, then added it to 5cm of hydrochloric acid. I kept the beaker placed over the paper with the cross and timed how long it took for the cross to disappear. I varied the temperature each time I did the experiment, as to follow my aim and by conducting the experiment and taking five readings for different temperatures, these are the results I collected. Temperature �C Time for cross to disappear 25 35 45 55 65 38 seconds 25 seconds 18 seconds 11seconds 9 seconds From the results I can see the overall experiment worked as I expected. The readings are fairly reasonable, and I have been able to combat any anomalous results. This tends to prove the accuracy of my experiment. I believe the preliminary experiment was very useful it has helped me decide what method I will use in my investigation, how I plan to set it out and what I need to change to improve the experiment to provide precise results. Graph to show preliminary results and predicted graph For the predicted graph for the results, I believe this is approximately what my results will look like when plotted on a graph. The results will slope down with negative correlation. The preliminary is a way for me to recognise I'm conducting the experiment correctly, and will be prepared for the real one. For the preliminary work I did the experiment but didn't repeat it, as I only wanted to see that the values I was to be using are accurate. This helped me plan my actual investigation, as I learnt through my mistakes. ...read more.

Conclusion

Nevertheless, I feel with extra time, I could have repeated the experiment and made it further accurate and adapted it to other variables, i.e. concentration or adding a catalyst. These are ways I could expand to the original experiment. The particle theory says that for a chemical reaction to occur there must be a collision at a certain speed and certain angle. Also the factors that affect the rate of reaction are the surface area of the solid reactant, the concentration of the reactant, the presence of a catalyst, the amount of pressure exerted on it and it's temperature. In this experiment, temperature was my focus, and I able to draw a conclusion that temperature does in fact, affect the rate of a reaction, in that when the temperature is higher the reaction takes less time. In the experiment I didn't use any device to help me in my investigation, though to improve my experiment I could use a different method to perform the experiment. I could use a device to help me in my investigation to measure the rate of a reaction. The apparatus I would use is a piece of equipment called a data logger. This will help me measure the rate accurately. A data logger is an electronic instrument that records measurements including (temperature, relative humidity, light intensity, on/off, open/closed, voltage, pressure and events) over time. The data logger is connected to a personal computer. Then a turnkey software is used to select logging parameters (sampling intervals, start time, etc.) and initiate the logger. The logger records each measurement and stores it in memory along with the time and date. The logger is then reconnected to a personal computer and the software is used again to readout the data and see the measurements as a graph, showing the profile over time. Data loggers incorporate the latest in digital technology which makes them smaller, less expensive, more accurate and more reliable than chart recorders. Therefore, it is an improved and more sufficient way of measuring the temperature, and would help me produce adequate results. A remote data logger Nafisa Ahmad 11S ...read more.

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