For my experiment I am going to attempt to observe the reaction between sodium thiosulphate and hydrochloric acid.

W ill this affect the Surface Area?

The size of solid particles or surface area will affect the rate of reaction because if the reactant is a solid then you break it up in to smaller pieces which will increase its surface area. This means the particles around it in the solution will have more area to work on so there will be more useful collisions. If the sold particles is not broken up into smaller pieces then this would mean that the particles around it will have less area to work on and there will be collisions but it will take a longer time for the particles to break the solid particle down totally

Using my preliminary experiments I decided on using the following apparatus:

2 measuring cylinders

1 conical flask

1 stopwatch

1 piece of paper with an X marked on it

1 pair of goggles

Method

I will do my experiment but first I will conduct a preliminary investigation before I go onto the main experiment this is due to making sure everything is right in preparation for the main experiment. By doing a preliminary experiment I can adjust any problems I may find.

1. I will set up apparatus shown in this diagram

HERE THE SULPHATE THIOSULPHATE AND HYDROCHLORIC ACID ARE REACTING AND THE TIME TAKEN FOR THE PERCIPITATE TO FORM OR THE ‘X’ TO DISAPPEAR IS BEING COUNTED ON THE STOPWATCH

2. I will record the room temperature
3. I will measure the amount of hydrochloric acid and the amount of sodium thiosulphate solution require. Using a measuring beaker to measure the volume.
4. I will place a white sheet of paper marked with a cross such a ‘X’. The I place the the sheet underneath the conical flask.
5. I will mix the two solutions in the conical flask
6. I will start the stop watch
7. After I have witnessed a reaction I will note my results on a results table
8. I may alter the experiment by changing the amounts of either base solution (water) or even changing the amount of Hydrochloric acid. This may improve and make clearer results I hope to get in the main experiment which are in my prediction.

We took the room temperature before the experiment which was 22 degrees

Now I will do my Preliminary experiment

Conclusion

In my experiment I found that during the reaction between Hydrochloric acid and Sodium Thiosulphate, when the Hydrochloric acid is added to sodium Thiosulphate solution, a fine deposit of sulphur is formed. The sulphur makes the solution cloudy. As more and more sulphur is formed, the solution becomes more and more cloudy. Soon it becomes impossible to see through the solution.

Results

I have plotted the results of the preliminary experiment  and places a line of best fit in

After making minor changes from the preliminary experiment. Iam now going to do the main experiment . This is done the same as the preliminary test to keep it a fair test.

For the main test I altered the Hydrochloric acid by adding a further 5cm2 to the experiment. This was to  This lead to the sodium Thiosulphate and the water having up to 15cm2 instead of 10cm2 of solution in at one time. Also I will now take 2 result readings then work out and average

For the main experiment the classroom temperature had altered by 1degrees and now stood at 23 degrees

Results from Main experiment

Now I will work  out the average times in seconds

I will now construct a results scatter diagram on the next page

Conclusion

In my experiment I found that during the reaction between Hydrochloric acid and Sodium Thiosulphate, When the hydrochloric acid is added to Sodium Thiosulphate solution, a fine deposit of sulphur is formed. The sulphur makes the solution cloudy. As more and more sulphur is formed, the solution becomes more and more cloudy. Soon it becomes impossible to see through the solution. From my one over time graph I have found my results take up a similar structure.

Evaluation

My results were of a particularly accurate standard as I did each concentration the reaction was taking place twice and calculated an average from these times. There were no strange results within my results table and I think that this was because of the extreme caution and care that I put into making sure that the experiment was set up correctly with careful measuring of chemicals. Things I could of changed were the heat I could of changed the heat which would of set up a further experiment. Overall I am pleased with my experiment. Adaptations to this experiment could be made I believed the results weren’t totally accurate as the human eye isn’t totally trust worthy as a judge. Maybe in future experiments a machine featuring a light beam could be used instead of the traditional ‘X’ and when the beam is broken it automatically stops a build in stop watch.