The description of Mage Hand says:
You can use your action to control the hand. You can use the hand to manipulate an object, open an unlocked door or container, stow or retrieve an item from an open container, or pour the contents out of a vial (PHB p.246)
while the description of Acid (vial) says:
As an action, you can splash the contents of this vial onto a creature within 5 feet of you or throw the vial up to 20 feet, shattering it on impact. In either case, make a ranged attack against a creature or object, treating the acid as an improvised weapon. (PHB p. 148, "Adventuring Gear")
However Mage Hand also states:
The hand can’t attack, activate magic items, or carry more than 10 pounds.
So the question is can Mage Hand pour out Acid (vial) onto an enemy? And if it can be poured, would the damage require an attack roll from the caster or a dex saving throw from the target? If it is an attack roll, then what does it scale off of and how would proficiency be determined? If it is a saving throw, then how is the DC calculated (either a specific DC to the vial/Mage Hand or the caster's spell save DC)?