"What Affects How Quickly Sodium Thiosulphate (thio) Goes Cloudy?"

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            May 07

“What Affects How Quickly Sodium Thiosulphate (thio) Goes Cloudy?”

Skill P  Planning

Concentration can change the speed of the reaction in two ways:

  • The higher the concentration of the thio, the faster the rate of reaction, and the shorter the time span.
  • The lower the concentration of the thio, the slower the rate of reaction, and the longer the time span.

I will be using first-hand experience evidence, as it will be a more reliable investigation, if I were to use secondary sources, the results may not be accurate enough to analyse.

I will record my data in a table and then plot it onto a graph; I will use a wide range of equipment.

For my experiment, I will use the ‘disappearing cross’ method. To allow me to make this test a fair test, I will use the same cross for all the tests. The disappearing cross method is whereby I have a cross drawn on a piece of card, and is laminated, (to help stop the liquid solution from damaging the card). The cross is placed under the conical flask. As the reaction takes place, the solution becomes cloudy and the cross gradually disappears.

Being as I am using Hydrochloric Acid and Sodium Thiosulphate, I must ensure that I have protection from the liquids; therefore I will wear goggles. In order to make my experiment an accurate experiment, I will observe the cross and wait for it to disappear. When I think that the cross has disappeared, I will blink once, (with the eye that I use for observing); in order to ensure that the cross has actual disappeared.

In this experiment, to help make it a fair test, I will keep the volume of Hydrochloric Acid the same. I will change the volume of thio and distilled water. As you may have noticed, I have not mentioned temperature; this is because, I will not be using any immediate heat on the solution, but in fact, the room temperature will change, concluding that the temperature of the solution may have an effect on the results. I will decrease the thio from 25cm³, (1M), to an absolute minimum of 1cm³, (0.04M), thio. The equation for finding out the strength of the thio was 0.04 x (volume of thio). By doing this, it will make the thio react slower and turn the solution cloudy slower: this is because of the collision theory.

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If there are lots of acid particles and thio particles, there will be more collisions, as there is not enough space for the atoms to move around meaning that the atoms would collide more often into one another. If there were fewer thio particles and the acid particles are unchanged, resulting in fewer collisions as the atoms would have more space to move around in and they would not collide as often.

Prediction

For this experiment, I predict that the higher the concentration of sodium Thiosulphate, the faster the rate of reaction will be, this is because, ...

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