g TITRATION OF ACIDS AND BASES Measure exactly 20 drops of a dilute acid such as vinegar and put these into a testtube Add one drop of indicator either methyl orange or phenolphthalein is satisfactory To this mixture of acid and indicator add a dilute base drop by drop and count the drops Within experimental error it will always take the same number of drops to neutralize the 20 drops of acid provided that the same dropper is used A teat pipette makes a satisfactory dropper If the concentration of the acid is known the concentration of the base can be estimated by comparing the numbers of drops of acid and drops of base that just react