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To Investigate How The Concentration Of Reactants Affects The Rate Of a Chemical Reaction.

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Introduction

To Investigate How The Concentration Of Reactants Affects The Rate Of a Chemical Reaction. Introduction/background information For our coursework we are doing an experiment to see how different concentrations of reactants affect the rate of a chemical reaction. * What is a reaction? A reaction occurs when two particles join together to produce different product(s) * What is a reactant? A reactant is a substance that reacts with another substance * What is a rate? The rate is the measure of how fast or slow the reaction takes place * How can we measure the rate? You can either measure how much of a reactant is used up in a given time or how much product is given off in a given time Collision theory Collision theory tells us that particles must collide before they can react and they need enough energy to break their bonds in order for the collision to be successful and result in a reaction. The energy needed is called activation energy. During a reaction the rate does not remain constant, because at first there are lots of particles so it is easier for them to collide. Later on in the course of a reaction there are fewer particles left to collide. The chance of a successful collision can be affected by different variables. These include: * Temperature- the hotter the temperature, the faster the particles are moving and the more likely they are to collide successfully. ...read more.

Middle

Use a stop clock to time the experiment. 9. Record your results in your results table. 10. Repeat trial with each different concentration of acid 11. Complete two series of trials Fair Test In order to make this experiment a fair test I will change one variable and keep the others the same throughout. The variable I will change is the concentration (molarity) of the acid. I will keep the following variables the same: * The amount of Calcium Carbonate Powder must stay the same because if there is more powder, it is likely to speed up the rate of reaction because there will be more particles to react. * The amount of Dilute Hydrochloric Acid must stay the same for the same reason * The temperature of water used must stay the same because if the water is hotter it will make the gas expand causing the measurement of the volume of gas produced to change. * The size of delivery tube must stay the same so that the gas produced can always get through at the same rate * The stop clock should start at 0.00 each time so we can measure the time accurately. * The amount of movement should be the same each time because moving it will give the particles more energy speeding up the rate of reaction. ...read more.

Conclusion

Between 0.4m and 1m, the amount of carbon dioxide produced almost doubles. The results of the two trials I did were very similar except for the trials with the acid at 0.8m. There was a difference of 20cm3 between the two trials, which is roughly a 10% difference. This might have been caused by: * Different room temperatures * Causing movement when you put in the Calcium Carbonate powder * Inaccuracy in timing * Inaccuracy in measuring the amount of acid * Inaccuracy in measuring the amount of Calcium Carbonate Overall Evaluation Although the experiment agreed with my prediction there are a lot of variables that were not controlled very well. * I did not ensure that the experiment was done in an environment at a constant temperature. As I did it over a number of days the room temperature may have varied and affected the results. I could improve this by controlling the temperature more carefully. * The size of the particles of calcium carbonate may not have been consistent. I could improve this by sieving it to make sure I used particles of more closely the same size. Overall I think the experiment generally went well as the results seemed to agree with theory and my prediction. However, this is a very small sample of trials and for the results to be more reliable you would have to carry out more trials. Janine Ranson chemistry coursework 04/05/07 ...read more.

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