The experimental procedure has you wash your thermometer and dry it after you measure the temperature of naoh solution and before you measure the temperature of the hcl solution. why

If you do not wash and dry the thermometer after every time you use it in this scenario, the temperature could be affected by the NaOH residue. This could make it so that your findings were inaccurate, so in order to be efficient, this precaution needs to be taken.