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How concentration affects rate of reaction

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Introduction

Chemistry IGCSE Coursework V�ctor Toledo Science 10A How concentration affects rate of reaction AIM: We wanted to see if changing the concentration of one of the reactants also changed the rate of reaction by changing the ratio of acid to the other reactant. To test this we used calcium carbonate and hydrochloric acid: PLAN: We were going to calculate how concentration affected reaction rate by reacting the calcium carbonate and acid in a conical flask and then collecting the carbon dioxide that would come out in a measuring cylinder filled up to the top. Then we would record how much gas was collected during a minute and repeat these steps with a different concentration of the acid. ...read more.

Middle

4. Get hold of the stopwatch and be prepared. Tell somebody to hold the tube where the entrance to the cylinder is because it might pop out because of the gas' force. Add the two reactants into the conical flask and quickly put the stopper. Start timing immediately. 5. Let 1 minute pass and record the volume of gas in the cylinder. 6. Repeat steps 2-5 but changing in step 3 the concentration of acid by diluting it with water: 20:5, 10:15, etc. VARIABLES Things that were different - Concentration of acid: This was the aim of the experiment, changing concentration to see if rate of reaction also changed. Things that were kept the same - Shape of flask: Depending on the shape of the container, particles would collide more/less often, so results would be inaccurate. ...read more.

Conclusion

Therefore, when concentration is high, reaction rate increases; when it is low, rate of reaction increases. EVALUATION: The reason why varying concentration affects reaction rate is because of the collision theory. This states that the reactant particles collide together and form the chemical reaction. If concentration is high, there are more particles in the same volume so collisions occur more often. There was an anomalous result in our experiment. In the trial for 1.2 moles of concentration there was a peak and instead of 84 it should have been in between 40 and 61. The problem might have been that the mixture was mixed too much, there was too much of calcium carbonate, the stopper was put much faster than others. We could have improved timing, more accurate measurements and making sure that no gas escapes before getting to the cylinder. ?? ?? ?? ?? ...read more.

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This report includes the basic elements for a sound laboratory report. It is significantly limited by the small amount of data collected and the basic and brief evaluation of that data. What was written was done well.

Marked by teacher Cornelia Bruce 17/04/2013

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