In this experiment, we are going to experiment how the concentration of sodium Thiosulphate affects the arte etc of a reaction with hydrochloric acid.

The actual Equation is:

S2O3    (aq) + 2H  (aq)                            H2O(l) + SO2 (g)  + S (s)

These are the forms - (s) is Solid, (l) is liquid, (g) is gas and (aq) is aqueous, meaning dissolved in water.

This is a word equation of what’s happening:

Thiosulphur + Hydrochloric Acid                           Water + Sulphur Dioxide + Sulphur.

Aim: Our aim for this experiment is to find out how the Concentration of Sodium Thiosulphate affects the reaction rate with Hydrochloric Acid.

Method: In this experiment, we are going to have to get a piece of A4 paper, and draw a cross on it (2cm by 2cm). We shall then place the Conical flask over the top of it. We shall then get a timer, add the Hydrochloric acid to the Flask, and from the point that we add the ST, shall start timing. This is a diagram of what we shall be doing.

 

Equipment:

• Sodium Thiosulphate (ST)
• Hydrochloric acid
• Paper with a 2x2cm cross on it
• A timer
• 2 measuring cylinders
• A conical flask

Safety:

For safety we are going to have to follow these rules:

• Goggles must be worn – in case Hydrochloric acid gets rubbed into eyes etc.
• We have to be careful with the Glass flask, this means no running or messing around etc.
• We must follow standard lab rules, such as no shouting etc.

Fair Test:

To keep this experiment a fair test, we must ensure everything that needs to be the same must stay the same. We have control over changing the volume of acid, the volume of ST and the strength of the ST. We must keep the volumes of the ST and the HA the same. This is very important, as it could mess up our results.

We are going to change the Independent variable (ST). Our dependant variable will change of this. Our only controlled variable, which we will keep the same, is the volume of acid and the volume of ST.

Prediction:

My prediction is that the stronger the concentration of ST the faster the water will turn cloudy. This means the rate of water turning cloudy will be faster the stronger the concentration of ST.

Results:

My Results:

Class Results

I shall now get an average for every group for my results and the class results.

My Results

Class Results

These tables show me how the weaker the concentration gets the longer it takes for the ST solution to get cloudy.

Graphs:

 P.T.O for graphs.

 

Graph analysis

From both of my graphs I can clearly see that the stronger the solution of ST the quicker the reaction works. This means that my prediction is correct and that I have found out my aim.

There is a rapid decrease in time between 10(g/1) and 20(g/1).

This happens because there is a bi change in the number of Sodium thiosulphate particles. The more particles there are the faster the reaction will take place because there is a greater chance of an ST particle hitting a Hydrochloric acid particle.

Evaluation:

Overall I think my experiment was a success. I had controlled my variables well and made special care not to get the wrong concentrations of ST in different tests. The experiment can also shows how well I did the experiment due to the accuracy of the points. They are very smooth and produce a nice curve.  If some of my results were wrong, then there would be an uneven bend or dent in this curve.

We were very careful using the acid and equipment, which also made our experiment more accurate. There was no messing around with tools or different solutions.

We measured everything carefully too, to ensure better results.

Overall, we found that the higher the concentration of ST the faster the reaction.