Characterizing azobenzene molecules by infrared spectroscopy Retrieve the rack from the sample rack station. Use the solid station to add 0.18 g of azobenzene. Use the liquid station to add 8 g of dichloromethane. Use the magnetic stirring station to stir the mixture at 500 rpm for 10 minutes at 25 ℃. Use the sample preparation station to make the sample of azobenzene. Use the infrared spectroscopy station to test the infrared spectrum of the sample. Place the rack into the sample rack station.