I will keep repeating this experiment but each time I will be diluting the Sodium Thiosulphate to see if this changes or affects the reaction. I will be using the following dilutions (making sure volume of the water, Sodium Thiosulphate and hydrochloric acid never exceed 60cm ).
KEY
W= pure distilled water S-T= Sodium Thiosulphate H-A=Hydrochloric Acid
I will record the times of the reactions and repeat each experiment twice so I can find and average time for each experiment, which will make it a fair test. Also I will keep a thermometer with me at all times and check before each experiment that it is a room temperature because different temperatures my alter or affect my results.
PREDICTION
In this experiment I predict that the rate of reaction will change depending on the concentration of the solution. I predict that as the volume of Sodium Thiosulphate is diluted with pure distilled water the longer it will take for a reaction between Sodium Thiosulphate and hydrochloric acid to take place.
EQUIPTMENT
In this experiment I will need the following.
- Sodium Thiosulphate
- Hydrochloric Acid
- 3 Conical flasks
- Thermometer
- 3 measuring cylinders
- Water
- Glasses
- Piece of paper with a pencilled cross
- Stopwatch.
- Apron
FAIR TEST
To make my experiment a fair test it is very important that all the way through the experiment the solution is kept at a constant volume at all times. I will be taking the temperature to make sure that it is always around the same temperature as any alterations or changes may make my results unreliable and may also change or affect the rate of the reactions. I will have to ensure that none of the equipment I will be using is contaminated and has all been properly cleaned. I will be using a stopwatch to get a more accurate time of reaction.
SAFETY
A pair of goggles will be worn during the heating part of the experiment in order to protect the eyes. An apron will also be worn to protect the skin and clothing.
COLLISION THEORY
A chemical reaction can only occur between particles when they collide (hit each other). Particles may be atoms, ions or molecules.
There is a minimum amount of energy which colliding particles need in order to react with each other. If the colliding particles have less than this minimum energy, then they just bounce off each other and no reaction occurs.
This minimum energy is called the .
The faster the particles are going, the more energy they have. Fast moving particles are more likely to react when they collide. You can make particles move more quickly by heating them up (raising the temperature).
RESULTS
CONCLUSION
At the beginning of the experiment, using my scientific knowledge. I predicted that the more the solution was diluted the longer it would take for a reaction to take place.
When carrying out the experiment I noticed a pattern forming. At the end of the experiment I could clearly see that all my results were true to my prediction. The time of each reaction increased gradually. This shows the prediction was correct. (The more diluted the solution, the longer it will take for a reaction to take place).
EVALUTION
I think that my experiment was a success, my prediction and results were clearly correct. I had no “odd results” which enabled me to plot a clear graph with a clear line of best fit.
I believe that I kept the right variables the same all the way through e.g. constantly at room temperature.
It may of helped me to conduct a pilot experiment to practice recording information and make it easy to no how to handle equipment and monitor the experiment correctly. But I was unable to do that due to illness.
I believe that I did my best to keep the test fair and I believe my results to be correct.
