The purpose of this investigation is to record the amount of time taken for a reaction to occur when sodium thiosulphate is mixed with hydrochloric acid.
The equation for this reaction is:
Na2S2O3 + 2HCl → 2NaCl + S + SO2 +H2O
Sodium thiosulphate (Na2S2O3), after reacting with Hydrochloric Acid (HCl) produces yellow sulphur, which is the cause of the solution becoming cloudy.
The amount of time taken for the reaction to occur is known as the reaction rate. The rate of a reaction can be commonly explained by Collision Theory. This theory states that in order for a reaction to occur, the particles of each reactant must collide together, with successful collisions resulting in chemical changes. Activation energy is released when the particles hit each other and whether the collision is successful or not is dependant on the amount of activation energy present. The energy's purpose is to allow the element to break its current bonds and form new ones.
In the case of liquid solutions, the concentration of the elements is also important when considering whether the reaction will be successful or not. The lower the concentration, the fewer particles there are to collide with each other, slowing down the rate of reaction.
Based on this theory, one can predict that the rate of reaction will decrease as the concentration of the Hydrochloric Acid decreases as well.
In order to perform the experiment, the following Apparatus must be used:
50ml of Na2S2O3 – Sodium Thiosulphate, a reactant
10ml of HCl – Hydrochloric Acid, a reactant
Conical flask – Used to contain the solution during the reaction
Measuring Cylinder – Used to measure the amount of Sodium Thiosulphate used in each experiment
Stop clock – Used to measure the amount of time taken for reaction to take place
Card with cross – Used to identify when the reaction has finished.
The input variable in this...