Acid flask

You can throw a flask of acid as a splash weapon with a range increment of 10 feet.

Source Core Rulebook

A direct hit deals 1d6 points of acid damage. Every creature within 5 feet of the point where the acid hits takes 1 point of acid damage from the splash.

Alchemical Power Components

Source Adventurer’s Armory

A common flask of acid has many uses as an alchemical power component, particularly with attack spells.

• acid arrow (M): The spell’s acid lasts 1 round longer than normal.
• Acid Fog (M): The fog’s radius and height increase by 5 feet.
• acid splash (F): The spell deals +1 point of damage.
• acid splash (M): The spell lasts 1 round longer than normal.
• dispel magic (M): Using acid as a material component while attempting to dispel or counterspell a spell or effect with the earth subtype gives you a +2 bonus on your dispel check. This bonus applies whether you are using dispel magic, greater dispel magic, or some other spell that you can use for counterspelling (for example, if you have the Improved Counterspell feat).
• grease (M): The grease is acidic and deals 1 point of acid damage per round to any creature in the area or holding the greased object.
• Wall of Ice (M): For each flask of acid used as a power component, you may designate one 10-foot square of ice wall that, if broken through, deals 1d6 acid damage in addition to the normal cold damage.

An alchemical power component is an alchemical item used as a material component or focus for a spell in order to alter or augment the spell’s normal
effects. What follows is a sample of these effects using this item as a component; your GM may allow other combinations.

• _{Spells followed by an (M) expend the alchemical item as a material component;}
• _{Spells followed by an (F) use the item as a focus and do not expend it.}

In both cases, the alchemical item does not have its normal effect and does not affect any other parameters of the spell. You cannot use the same item as both a focus and a material component at the same time.

Using Splash Weapons

 Make a ranged attack against an unoccupied grid intersection (AC 5 plus range penalties.)

You Hit: Creatures in all adjacent squares are dealt splash damage. No creatures take direct hit damage.

You Miss: First, roll 1d8 to determine the misdirection of the throw.

•  1 – Falls short (straight line towards the thrower.)
•  2 through 8 – Count around the target creature or grid intersection in a clockwise direction.

Then, count a number of squares in the indicated direction equal to the number of range increments thrown. The thrown object lands that number of spaces away from the target.

Finally, the item deals splash damage (if any) to all creatures in the square it lands in and in all adjacent squares.