The spell Acid Splash describes itself as:
You hurl a bubble of acid.
This is followed with the damage description:
1d6 acid damage. This spell’s damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).
The item Vial of Acid is simply referred to as acid and notes its damage as:
2d6 acid damage.
The question is can the caster catch the bubble in a flask or container
(they would then later pour it into a vial)?
Can the caster simply drop the bubble instead of hurling it?
If the caster can store the acid then would it deal damage equal to Acid Splash or to that of vial of acid?
If it deals damage equal to Acid Splash then what tool proficiency would be required to refine it
(Artisan's tools (alchemist's supplies), Herbalism kit, or Poisoner's kit) ?
Best Answer
By the RAW, probably, but literally no-one will ever agree with you about this.
Combining the spell description
with the rules on 'Instantaneous' spell effects
the absolutely most likely form of the spell is that it creates a bunch of acid that is in motion and is a created object. The description of hurling acid on people doesn't work with 'harms a creature' or 'alters a creature' - if it described 'burning a creature like acid was poured on it', sure, that's a metaphor for the type of damage (harm) the creature is receiving. But it refers to throwing actual acid at people and ergo, it is creating that acid in the first place.
Magic that only exists for an instant is not long enough for people to dodge with Dexterity saving throws and for acid to fly 60' away etc. That amount of time would allow counterspelling or not be 'instantaneous'. It is, however, long enough to create some acid-in-motion. And as 'creating' an item is explicitly something instantaneous spell effects do, it fits the listed facts about Acid Splash a lot better than any other explanation.
However, in general the attitude of the rules of 5e and the most common attitudes amongst it's players means likely few or no GMs or players of 5e DnD will use this reading or acknowledge it's relevancy. The entire philosophy of the game is almost directly against this, which would be termed by both the authors of the game and the most outspoken proponents of the system as 'an exploit/cheat and against the intent of the rules'. If not simply making an argument that the RAW doesn't say that in the first place.
Simply put, if your group is interested in this sort of 3.5e 'using abilities in ways they weren't intended', then yes, Acid Splash can be stored.
However, most 5e players will disagree strenuously - and what the rules suggest, in that circumstance, is rather irrelevant.