Apparatus
To do my experiment I will the following:
Flask
Measuring cylinder
2 beakers
Stopwatch
Paper with black cross on it
Goggles
Fair test
To make this test fair I will make sure that I will make sure that I will wash the beakers out for the other concentration test to take place. I will make sure that I stop the stopwatch as accurately as possible to get the fairest results.
Measurements
I will be measuring the concentration of hydrophilic acid in molars (m) these are the four different concentration I will be using in the experiment, 0.5m, 1.0m, 1.5m and 2.0m
Method
To do this experiment I will start by measuring out 10ml of 0.5m of HCl and adding it to a beaker containing 10ml of sodium Thiosulphate which is placed over a piece of paper with the cross marked onto it. I will then time how long until I can no longer see the cross through it. Once I cannot see the cross I will stop the stopwatch and take the time down. I will then wash out both of the beakers and do the same but changing the concentration of the HCl to 1.0m then 1.5 and finally 2.0m.
Prediction
What I predict to happen is that as I increase the concentration of HCl the faster it will take for the reaction to take place. I have predicted this due to my knowledge of the collision theory. The collisions theory is based on the assumption that it is necessary for a reaction to take place by the molecules in each chemical to collide with one another. Which means that if I increase the concentration of HCl there with be more molecules of HCl to collide with the molecule in the sodium Thiosulphate, therefore making the reaction faster.
Results
What I found out in my experiment was the each time I increased the concentration of the hydrochloric acid the less time it took for the cross to disappear. My results match my prediction very well because I predicted that as I increased the concentration of the HCl that it would take lass time for the reaction to take place.
Evaluation
I believe that I have done my experiment well and that I hav a set of accurate results that I can be sure about my conclusion. I can be sure that my results are correct as I can relate it to the collision theory, which basically tells me the same thing.
My method of this experiment was roughly accurate. I made sure that I washed the beakers out before moving on to the next part of the experiment. I measured out the same amount of sodium Thiosulphate and I only changed the concentration of the HCl.
If I were to redo this experiment I would use four different sets of beakers for the different concentrations. This would give me more accurate results. I would also do more different ranges of concentration so that I had a bigger range of results to analyses. I could also extend my investigation by not only investigating how the concentration effects the reaction time but by also investigating how temperature effects the rate of reaction. As the collisions theory states that the particles have to collide with one another to create a reaction. The increase of heat effects how the fast the particles travel around, so the more the temperature is increased the faster the particles more around increasing the risk of collision.
