See the Knock spell, which allows you to make a spellcaster check (with +10) against the lock's DC. Success means the lock will be disabled.
Knock opens stuck, barred, or locked doors, as well as those subject to hold portal or arcane lock. When you complete the casting of this spell, make a caster level check against the DC of the lock (see table at right) with a +10 bonus. If successful, knock opens up to two means of closure. This spell opens secret doors, as well as locked or trick-opening boxes or chests. It also loosens welds, shackles, or chains (provided they serve to hold something shut).
We are in the realm of subjective GM Fiat now, we don't know the details about this chest, what material it is made of, what kind of lock (and it's material) it is made of, so it is really difficult to brainstorm a bunch of ideas and your GM could simply say "nope, that doesn't work because -reason-".
Regardless, it is commonly accepted that a strong acid, like the one from an Acid Flask, should be able to destroy a metal lock if carefully applied to it, with a bit of patience. Speaking a little about physics, a bronze lock could be corroded using Nitric acid, Hydrochloric acid could destroy tin. While iron and steel locks would take some time, but a couple of acid flasks (or the Acid Splash cantrip) should be able to destroy it.
But again, this is completely subject to GM discretion, from Destroying Objects:
Some energy types might be particularly
effective against certain objects, subject to GM discretion.
Finally, you also got the Rusting Powder, which exists to corrode metal locks:
This flaky brown powder derived from rust monster fluids causes iron and similar metals to corrode and fall apart. If you apply a dose of rusting powder to a metal lock or trap as part of using the Disable Device skill, you gain a +5 alchemical bonus to open the lock or disable the trap, but there is a 75% chance that the mechanism is destroyed and cannot be used afterward. If the check fails, the mechanism is destroyed. A destroyed lock cannot be unlocked (but still counts as locked for the purpose opening the locked object). (...)
Rusting powder is sold in a paper tube; you apply it by tearing the ends off the tube and blowing the flakes into the target device. Rusting powder does not affect gold, silver, copper, bronze, brass, or mithral, but easily affects iron, steel, and adamantine.