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Rates of Reaction - Equation for sodium thiosulphate.

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Aim To find out how changing the temperature affects the rate of reaction. Background Information The rate of reaction is the speed in which the reaction takes place. Many things can affect the rate of reactions. The more particles there are in a given space the more likely it is that they will bump into each other. The rate increases as particles hit each other more frequently giving more opportunities for a reaction to occur. The particles gain more energy therefore gain speed and particles are then more likely to collide. Equation for sodium thiosulphate Na2S203 + 2HCL 2Nacl + H20 + SO2 + S (aq) (aq) (aq) (l) (g) (s) These four variables will affect the rate of reaction TEMPERATURE: - by increasing the temperature, the atoms are given more energy to move, and thus they move faster and strike other atoms harder SURFACE AREA: - if a substance had a large surface area, another substance reacting with it would have more reactant atoms to collide with at any one time, increasing the rate of reaction. CONCENTRATION: - If a solution is more concentrated, then there are more particles of reactant between fewer water particles, resulting in more collisions between reactant particles and thus an increased rate of reaction. ...read more.


I will do 6 reactions at 10?C intervals 20, 30, 40, 50, and 60. When the acid is added to the sodium thiosulphate I should see it produce a yellow precipitate. I will begin timing the reaction as soon as I add the acid and I will stop timing when the cross has "disappeared" which is when the solution becomes totally unclear. Apparatus * 2 Beakers * Conical Flask * 2 measuring cylinders (50cm3 & 25cm3) * Piece of paper * Pen * Stop clock * Safety glasses * Heatproof mat * Bunsen Burner Method 1. Collect and set up apparatus. 2. Draw an "x" large enough so it can be seen underneath a Beaker, on a piece of paper. 3. Measure out 40cm3 of the sodium thiosulphate and 5cm3 of the hydrochloric acid, in separate measuring cylinders. 4. Pour the sodium thiosulphate into the conical flask and place it on top of the piece of paper with the "x" 5. As soon as the acid and water has been poured in start timing with the stopwatch. 6. As soon as the "x" can not be seen anymore stop the clock 7. Repeat this several times with each measurement to get an average for accuracy. ...read more.


This would have allowed me to calculate if the rate of reaction is relative to concentration or not, and if not, the experiment may have provided clues also this may have given me an opportunity to try the test at exactly 37c so I can say with confidence that it backs my prediction. I also think that the timer was started either too early or to late, before all of the sodium thiosulphate had been added, so maybe the results were a little too slow or too fast, but that has not affected my actual goal, of proving that the more concentrated a chemical is, the faster it's rate of reaction. My results are not very accurate, but in my view it is only the correlation between concentration and rate of reaction that mattered in this experiment, although I would have been able to get more information on the quantity with more accurate results. I feel that the method was a good one, because it was clear and easy to follow. There was, however, one clearly anomalous result. This was probably caused by human error. If I were to try this experiment again, I would place a light in the place of the cross this would have been more clear to tell me if the cross had disappeared completely, . ...read more.

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