Procedure:

1. Select the weight of aspirin from the slider.
2. Click on the “Add aspirin button” to take aspirin in the R.B flask.
3. Click on the “Add NaOH” button to add 40 mL 10% NaOH.
4. Click on the “Next”.
5. Click on the “Reflux” button to reflex the content for 15 minutes.
6. Click “Next”.
7. Click “Transfer solution” button to transfer it into 250 mL standard flask.
8. Click “Make up solution” button to make up the solution upto the mark.
9. Click “Next”.
10. Select the volume of aspirin.
11. Click “Pipette out” button to pipette out the aspirin.
12. Click on the “box” in front of ‘Preparation of titrate’ we can see procedure of preparation of titrate (aspirin) after selecting the volume of aspirin. 
13. Click “Next”.
14. Select the titrant (sodium thiosulphate).
15. Adjust the speed of drops.
16. Click on the “Start” button to start titration.
17. Near the end point the colour just fades, then click on “Add Starch” button to add indicator.
18. Adjust the speed of drops.
19. Click on “Start”  button to continue the titration.
20. When blue colour disappears click on the “stop” button to stop the titration .

Note:- Here 50 mL brominating mixture (Blank) = 45.6 mL thiosulphate.