I am investigation how concentration effects the rate of reaction.

Sodium Thiosulphate reacts with hydrochloric acid forming sulphur, water, sodium chloride and sulphur dioxide. The sodium chloride is dissolved in the water and the water is still transparent. The sulphur is precipitated because it isn’t soluble. This can be seen because if turns the solution opaque as more sulphur is produced the solution turns more and more opaque. If the solution was left for a long time one could see the sulphur solid settled at the bottom. I will start timing from when the two mixtures are mixed till when the cross isn’t visible anymore. The equation is shown below.

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

1. The Sodium Thiosulphate and water solution were made and placed in a water trough.

2. The Hydrochloric acid was measured out into different boiling tubes and place also in the water trough.

The molecules are moving because they have kinetic energy. Liquid molecules have quite a lot of kinetic energy. They can roll over each other but still have weak bonds with one another. Molecules need kinetic energy because when they collide, they slow down and the energy is turned into potential energy. If the combined kinetic energies of the reactants are equal to or bigger than the activation energy needed they can overcome the barrier and reactions take place.

The eyesight will also be a variable because someone with good eyesight can see better that someone will poor and someone will good reactions will stop the stopwatch quicker. But because I will be doing al the experiments alone it will not effect me.

The container in which the reaction takes place will also effect the time it takes for the cross to disappear. If I use a boiling tube with a small diameter than a large diameter it will take longer for the cross o disappear because there will be less precipitate I will have to look through. I will keep it constant by using the same size boiling tube for all the experiments.

The results graph would look like this if my solutions were more concentrated

Some topics in this essay:
Sodium Thiosulphate, H2Ocm3 Concentration, Volume H2Ocm3, Thiosulphate Na2S2O3, reaction rate, Volume HCl, Volume Na2S2O3, sodium thiosulphate, Reactions Planning, activation energy, kinetic energy, HCl Concentration, Thiosulphate Washable, Fullick Revision, boiling tube, rate reaction, aq +, reaction rate reaction, energy explained, water trough, collision theory, + 2nacl aq, s + 2nacl, 2hclaq s +, + 2hclaq s,