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How the Concentration of Acid in a Solution affects the Rate of Reaction

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Investigation into: How the Concentration of Hydrochloric Acid in a Solution affects the Rate of Reaction Aim: This experiment was to observe how the concentration affects the rate of reaction between chemicals. The two chemicals used in our experiment were Sodium Thiosulphate and Hydrochloric Acid. Introduction: The rate of reaction is basically the speed of how fast the reaction occurs between two reactants. You measure this speed in seconds, and have to set an achieving limit, which is a standard point of the reaction where a change is noticed and that is where the time must be recorded. A reaction is the simply the collision of the particles in two different substances (reactants). This essay is about writing how we observed the chemical reaction we carried out. Now here's the bit where the story gets interesting... My Prediction: My prediction is that: as long as the chemicals react in the same amount as was set, the speed of the reaction will be faster as the concentration (molarity) of the Hydrochloric Acid is increased. I predicted this because generally, when something has a higher concentration, it reacts quicker than when it has a lower concentration. This theory is ~ "Increasing the concentration increases the rate of reaction". This is because when there are more particles present, there is more collision between the particles; this increases the rate of reaction. ...read more.


The concentrations of the Hydrochloric Acid were 1M, 1.5M, 2M, 2.5M and 3M. We did the experiment with each concentration 5 times to be totally accurate. Then, carefully, we put away the chemicals and we washed the apparatus that needed to be washed, and cleared up. This is an important part of an experiment as the "health and safety" policy is essential. Without carefully putting away the apparatus, the irritant chemicals and glass tubes could be harmful, and may be fatal. Results Table: Concentration Of Hydrochloric Acid (Mole) Time taken in reaction. 1stTime (mins) Time taken in reaction. 2ndTime (mins) Time taken in reaction. 3rdTime (mins) Time taken in reaction. 4thTime (mins) Time taken in reaction. 5thTime (mins) Average Time (mins) 1M 3.24 1.14 1.18 1.14 2.48 1:08:72 1.5M 1.08 1.02 1.05 1.13 1.13 1:00:82 2M 1.05 1.07 1.10 1.03 1.10 1:00:70 2.5M 1.06 1.07 1.03 1.06 1.08 1:00:60 3M 1.00 1.05 1.00 1.03 1.02 1:00:20 (Graph for table of results attached on next page) Conclusion: There are a few areas I want to cover in the conclusion about this experiment. The patterns I noticed occurring as the reaction continued were related to the variable reactant. The pattern was that when we added Acid with more concentration to the Sodium Thiosulphate, the reaction was faster. This means that the slowest reaction was when Sodium Thiosulphate reacts with Hydrochloric Acid with a molarity of 1M; and the fastest reaction was when Sodium Thiosulphate reacts with Hydrochloric Acid with a molarity of 3M. ...read more.


So there was no mix of molarity. That was a sensible idea to gain reliable results. The thing that concerned me was the results ~ We were unsure at what point to note the time, so the first set of outcomes were slightly dodgy. This confusion was first revealed when the cross underneath the conical flask failed to totally fade. So then we randomly stopped the time when we got fed up of waiting, and after that, we stopped the time when the some parts of the cross were not entirely visible. This made the outcomes similar to the pattern, and the "increasing concentration" theory made proved itself true in the practical. We could have also used computer sensors for timing which would have given us more accurate results. Also, repeating this experiment as many times as possible would lead to better results and a stronger conclusion. There are many different experiments that we could carry to investigate the rate of reaction. Some of these are: * Varying the temperature * Applying pressure * Increasing surface area of the particles * Using a catalyst My overall comment for this experiment is that: Despite using accurate but imperfect equipment, my practical was a complete success and matched the theory that "the rate of reaction is directly proportional to the concentration of the reactants. ?? ?? ?? ?? ~ Syed Jafri ~ 11 East ~ Chemistry Coursework ~ Page 1 of 7 ...read more.

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3 star(s)

This report is not very well structured and does not follow the scientific standard required. The only reason it achieved three stars is the reliability of the data collected. There are more specific improvements and strengths suggested throughout.

Marked by teacher Cornelia Bruce 17/04/2013

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