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Rate of Reaction sodium thiosulphate

Extracts from this essay...

Introduction

Rate of Reaction Investigation with Sulphuric acid and Sodium thiosulphate Aim: The aim of this is investigation is evaluating an aspect that affects the rate of reaction between sodium thiosulphate and sulphuring acid reaction. Hypothesis: I predict that when the concentration of sulphuric is increased and all volumes are kept the same, the rate of reaction for the reaction will increase because increasing the concentration of a reactant increases the rate of the reaction. There are more collisions as there are more particles in closer proximity when higher concentrations are present. Variable What factors? How they will be controlled Independent The amount of time taken between the changes of concentrations of sulphuric acid. Different concentrations of Sulphuric acid will be observed by diluting it with water in a 10ml measuring cylinder. Concentrations are changed for every 0.2 M concentrations. Dependent The amount of time for the reaction to take place until the marked cross disappears due to the cloudy being formed. The stopwatch will be started once the sulphuric acid is added immediately to the sodium thiosulphate. Controlled Temperature Pressure Catalyst Surface area Temperature of reaction is held under standard conditions: 298K. The pressure of this reaction will also be held under standard conditions of 1 atm. Catalyst - no catalyst is added to lower the activation energy of the reaction.

Middle

* Add the two mixtures into the beaker, simultaneously. * Start timing immediately * Observe the marked spot under the beaker * When the reaction is finished, the cloudy mixture is present and the cross should not be able to be visible. That's when the stopwatch should be stopped * Record the time taken for this reaction to happen. * Do three trials for each set of concentrations * Repeat this whole process for 5 different concentrations of sulphuric acid. Method for effective controlling of variables: * Do this experiment under laboratory conditions * At room temperature (not fluctuating) * 1 atm pressure * Make sure no catalyst is added * Make sure the size of the beaker is the same because of keeping the same surface area of liquids during the reaction. Raw data of results time taken for reaction to happen (marked cross is not visible anymore) (+/- 0.5 seconds) Concentration of sulphuric acid (+/- 0.2ml) (M) trial 1 trial 2 trial 3 0.20 12.30 12.45 12.01 0.40 11.32 11.56 11.45 0.60 9.98 10.23 10.38 0.80 8.21 7.59 7.48 1.00 6.82 6.21 6.44 Qualitative data: When products are formed then the solution changes from colorless to cloudy yellow/white and the marked cross disappears. Processed Data Concentration of sulphuric acid (+/- 0.2ml)

Conclusion

Improving the investigation In order to avoid these limitations and weaknesses, the experiment could have been improved. Knowing whether or not the reaction has stopped could be determined by light. If a light is shined through the beaker during a reaction and once the reaction changes color, the wavelengths could be measured through a device that would measure wavelength of light as they would change when the reaction has stopped from the colorless solution into a cloudy yellow/whitish. This is to be done so the reaction can be stopped without human perception. The number of trials that is repeated for this experiment should also be increased so that the raw data of results can give a more significant set of results that can show a relationship between rate and concentration to determine the order of the reaction. The concentrations of should be evaluated in smaller intervals such as concentrations between every 0.1M of sulphuric acid to make the results more valid. All other factors should be kept under control and measured before the experiment is conducted if this experiment was done. The assumptions that were made could have altered the rate of reaction. Temperature, pressure and surface are to be measured before hand and of course with no presence of a catalyst. ?? ?? ?? ?? 12.11.2008 Philip Mannas

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