I’ll watch the solution in the flask for when it turns opaque and I can’t see the black cross on the target card any more. I’ll stop the stopwatch and record the length of time the reaction took in my table of results. I’ll repeat this whole process again but changing the 1 gram of Sodium Thiosulphate to 2 grams, I’ll record the reaction time for this measurement and increase it to 3 grams and so on until I have results for weights of Sodium Thiosulphate up to 5 grams.
To keep the experiment safe I’ll wear goggles and stand up throughout the experiment. I won’t pour from the chemical bottle but rather use a pipette to move the Acid. This will also help to give us a more accurate measurement for the Hydrochloric acid and distilled water. To measure the Sodium Thiosulphate I’ll use electrical scales, and remember to zero them with the plastic dish on first before I start adding the Sodium Thiosulphate.
We did a preliminary experiment using the same method, and saw the reaction time decrease as the concentration increased. In this experiment I’ll be making five measurements one for each different weight of Sodium Thiosulphate I’m using. I’ll repeat the whole experiment once to give my self more reliable results.
Prediction
I predict that as we increase the concentration of Sodium Thiosulphate in the water, the reaction time will decrease, getting faster and faster. This is based upon my theory that when Sodium Thiosulphate and Hydrochloric Acid are mixed a reaction takes place, this must be true because if it were not then this experiment would be pointless, and that the more of one or the other will increase the reaction, I based this upon my observations that the more wood or gas the is the quicker the fire burns, hence a faster reaction. I may be wrong and the reaction may work the other way but I am prepared to stake that it doesn’t.
Results
Table of Results
Analysis
Clearly, as we increase the concentration of the Sodium Thiosulphate in the water, the reaction time becomes faster. But the large difference between the reaction speeds when using 1 and 2 grams of sodium thiosulphate is unusual this could have been further investigated with a measurement from maybe 1.5 grams of Sodium Thiosulphate.
By looking at the results from 2 grams to 5 grams I can see a steady decrease in reaction time. This can also been seen by looking at the line graph, created from these results.
The reason for these results is that when exposed to hydrochloric acid, sodium Thiosulphate turns opaque. The more concentrated the sodium thiosulphate is, the more of it there is for the hydrochloric acid to react with and therefore the quicker the process.
Evaluation
There were only a few problems in the experiment that we encountered. The first of which was the sensitivity of the scales this made it hard to precisely get the weight required, this was acquired over time though and didn’t serve too much of a difficulty.
The results were moderately accurate in relation to the method and equipment we were using.
The only odd result we obtained was the finding for 1 gram of Sodium Thiosulphate. This was because the 2 gram made too much difference in the reaction rate compared to 1 gram which was not powerful enough to give the reaction the speed to take place quickly.
If I were to repeat the experiment I would take a few measurements between the 1 gram and 2 gram markers, to make the results more accurate. When pouring the liquids the use of a funnel may have eased the process. But the overall experiment was a success and worked fine.
