FINAL VERSION Rates of Reaction

 

Rates of Reactionseen from the mix of HCl and hypo

Aim: To investigate the effect of the temperature of sodium thiosulphate upon the speed of the reaction of hydrochloric acid and sodium thiosulphate.

Hypothesis: Heating up the hypo should make the reaction occur at a faster rate. Cooling it will probably make the reaction slower.

Apparatus: dilute hydrochloric acid (1 M), sodium thiosulphate (hypo) solution (0.25 M), stopwatch, 50 mL and 10 mL measuring cylinders, 500 mL beaker, thermometer, sheet with black cross, 250 mL flask or 100 mL flask (whatever fits into the 500 mL beaker).

Method:

First, the experiment shall be completed with (20 degrees) room temperature sodium thiosulphate. This will then be completed for 25-30 degrees, then 40 degrees for the third one, and 50 degrees for fourth one.Heating up can be done with a water bath using a 500 mL beaker.

To begin, the flask must be placed on the piece of paper with a cross on it. 50mL of sodium thiosulphate is added to a flask. 5mL of hydrochloric acid in a measuring cylinder must be then be added and a stopwatch started promptly. When the cross is covered by the cloudy solution and cannot be seen any more from directly above, the stopwatch must be immediately stopped. Also, during the experiment, do not place any glass materials towards the front of the tables/benches. Place them at the back to prevent accidents.

Results

Temperature (°C)	Time (secs)
20	19.07
31	10.83
40	6.05
50	5.14

Discussion

Describe results; give explanations

The time taken for the clouding to occur became shorter. It was initially a very big difference between the two temperatures. 8.24 seconds was the difference we recorded after the second attempt. 4.78 seconds is the difference between our second and third attempts. By the time we were finishing our experiments, there was only a difference of 0.91 seconds. This is less than a second. I predict that the differences will become less apparent as the temperature rises. I do not know whether the speed of the reaction will decrease indefinitely. The rate is changed by the experiment substantially in the beginning. This then reaches its maximum speed as the temperature rises.

The concentration of the reactants were kept the same for all four experiments and therefore have provided no information on which to discuss. Sulfur, water, salt, and sulphur dioxide is said to form from the reaction and the sulphur is what caused the cloudiness. Sulphur dioxide is dissolved into the liquid. I think that if the reactants were a higher concentration the reactions would occur at a much faster rate.

Conclusion: The heating of the sodium thiosulphate solutions all contributed to a faster reaction rate, thereby proving the hypothesis that the reaction would occur quicker when heated.

Noah Nishihara Home Group T09