RP3- Effect Of Temperature On Rate Of Reaction Flashcards
What is the equation for this experiment?
Na2S2O3 + 2HCl —> 2NaCl + S + SO2 + H2O
Describe the method for this experiment
Add 10cm3 of acid to a beaker
Add 1cm3 of thiosulfate to a test tube, place it into an empty plastic container with a cross under it. Use a thermometer to record the initial temperature
Add 1cm3 acid to test tube, start stop watch and record time taken for cross to disappear. Record the final temperature
Calculate the mean temperature from both the initial and final temps
Transfer solution to a stop bath to neutralise
Repeat experiment, this time adding 55* water to the plastic container (wait a few mins to allow the thiosulfate to heat up). Repeat with at least 5 different temperatures
What is the stop bath? Why is it used and where should it be stored?
A beaker containing sodium carbonate and phenolphthalein. It neutralises the acid and sulfur dioxide that is produced (sulfur dioxide is toxic because it is a choking gas)
Keep in a fume cupboard
How do you know when the stop bath needs to be replaced?
When it changes colour from pink to colourless (because there is no sodium carbonate left and it is just acid)
Phenolphthalein: pink in base and colourless in acid
What safety measurements should be taken and why?
Wear eye protection and lab coat- HCl is an irritant
Perform the experiment in a fume cupboard to minimise the escape of sodium dioxide
Use a stop bath, so the acid and sulfur dioxide can be neutralised
What should be controlled?
Concentration of both acid and thiosulfate
Volumes of all solutions
What graph should be drawn?
1/T on x axis
ln1/t on y axis
(Rate is proportional to 1/t)
