We carried out 2 trial runs, this is because we wanted to compare both the methods to find out which was most accurate out of both of them. 1 TRIAL RUN 1 – How concentration of sodium thiosulphate affects rate In this experiment we did a trial run to familiarise ourselves with the experiment and the equipment.
It also helps us what kind of patterns we expect to get.
The concentration of sodium thiosulphate was changed by adding water.
The solution was tested to see if it goes cloudy by observing an ‘X’.
This is because we do not have enough data to prove that concentration affects the rate of reaction.
We will make sure the same person observes the ‘X’ and records the time.Introduction My investigation is about the rate of reaction.A rate of reaction is defined as how fast or slow a reaction takes place.Measure volumes of sodium thiosulphate and water using results table Add 3ml of HCL into the flask.Immediately time how long it took until the ‘X’ was no longer visible, how long it took for the solution to turn cloudy The person observing when the ‘X’ disappeared then recorded the time.Temperature - Heating chemical substances can make the molecules separate and move around faster.This can increase the speed with which they mix with surrounding molecules from other chemical substances, thus speeding up a reaction.Three Measuring Cylinders (two 10ml)(one 25ml) – Each used to accurately measure how much sodium thiosulphate, water and acid are used in the experiment.Pipette – Used to put small amounts of acid into a measuring cylinder because it holds small amounts of acid in it so I can receive an accurate measurement.Results of trial run 1: Concentration (%) Volume of sodium thiosulphate (ml) Volume of H2O (cm3) Volume of acid (ml) Time taken for ‘X’ to disappear (s) 20 5 20 2 319.46 60 15 10 2 34.86 100 25 0 2 18.5 3 Evaluation: One of the weaknesses of the trial run was that the person recording the time changed and this could of lead to slight deviation in the result.However, other factors like the room temperature and the amount of acid in the solution were kept controlled to keep the test as fair as possible.