Final answer:
A phlebotomy technician should allow the venipuncture site to dry after using alcohol to cleanse it because alcohol requires time for the antiseptic to take effect.
Step-by-step explanation:
The reason that a phlebotomy technician should allow the venipuncture site to dry after using alcohol to cleanse it is because alcohol requires time for the antiseptic to take effect. Alcohol is used to swab the skin for degerming before needle injection and it works by denaturing proteins and disrupting the microbial cell membrane. Allowing the site to dry ensures that the alcohol has enough time to effectively kill any bacteria or viruses on the skin, reducing the risk of infection.