The aim of this experiment is to find out and study how temperature has an effect on the rates of reaction. I am going to investigate the changes caused to the solution of hydrochloric acid and sodium thiosulphate when the temperature is increased.

Na2S2O3 (aq) + 2HCl (aq) › 2NaCl (aq) + H2O (l) + SO2 (aq) + S(s)

Other factors that affect the rates of reaction are:

* Increasing the Concentration - Increasing the concentration of a substance in solution means that there will be more particles per dm3 of that substance.

* Increasing the Pressure - gas at higher pressure will have more particles per dm3 of the particles (usually molecules) of the gas.

* Increasing the Surface Area - The greater the area of the solid surface, the more particles that can have a collision with it per second and the quicker the reaction rate is.

* Catalysts - A catalyst is frequently used to make a reaction go quicker.

* Energy - A chemical reaction always go together with a change in energy.

I predict that the higher the temperature, the more quickly reaction will occur. This is because with heat, the particles of sodium thiosulphate and hydrochloric acid have more energy. This causes them to move around more. It works like this for all substances, not just those two. Chemical reactions require collisions, and if particles are moving around more quickly they are obviously more likely to collide.

Safety:

Precautions to use whilst performing this experiment are:

* Wear goggles to protect eyes from chemicals that could be harmful

* Do not allow chemicals to come into contact with skin (could cause irritation or burns)

* Keep hair tied back to avoid flames and contact with chemicals.

* Do not allow skin to come into contact with the flame (Bunsen burner)

* Do not drop glass or breakable objects that can shatter and cause harm.

* Should stand to put a appropriate distance between student and the experiment.

These precautions should be carried out to assure the scientist and surrounding classmates do not come to any harm resulting from any faults or anomalies in the experiment.

Fair Test:

To assure no anomalies form in the experiments results, these precautions should be taken:

* Repetition of the experiment to eliminate anomalies in the results

* Equal measurements of both chemicals in all repetitions.

* Must have correct difference in temperature each time.

Ranges:

The range in temperature I will use in this experiment will go up in 10 Centigrade intervals starting with 10 centigrade and finishing in 100 centigrade.

Apparatus:

Apparatus:

* 1 thermometer

* 1 beaker

* 2 measuring cylinders

* 1 conical flask

* 1 tripod

* 1 gauze

* 1 heatproof mat

* 1 stopwatch

* 1 Bunsen burner

* 1 pair of tongs

* 1 pair of goggles

* 25ml Sodium Thoisulphate

* 5ml Hydrochloric Acid

Method:

5 ml of HCl and 25 ml of sodium thiosulphate are poured out into two measuring cylinders. A beaker is half filled with hot water from a tap. The water is positioned on top of a Bunsen on a blue flame. The water is heated to the needed temperature (10?C to 70?C) then the two measuring cylinders are taken out and the contents of both are poured into a conical cylinder. The time it takes for the X to vanish is timed and documented. The experiment is repeated using all the temperatures. The entire process is to be repeated.

Repeat results and averages will be taken to improve the reliability of the findings, and present solid grounding for the finishing conclusion. The repeat results will help to iron out any anomalies and the average will give a good summary of the results of the experiment. However if one set of results is entirely different to the last, a third experiment will be carried out to replace the anomalous set of results.

Pre-test:

Analysis:

This is because with more heat, the particles of sodium thiosulphate and hydrochloric acid have further energy. This causes them to move around more. Chemical reactions involve collisions, and if two sets of particles are moving around rapidly there will naturally be more collisions. However, the collisions require the particles to hit each other at a certain speed, and if this speed is not reached then the reaction will just not happen. So, at the high temperatures, more of the particles were travelling at a high enough speed to collide and react. At the lower temperatures it was more difficult for the particles to collide. Only some were able to reach the required speed and react.