Question

How would you solve gas laws problems with the given "at STP"?

Answer 1

Refer to the Explanation.

Explanation:

The most current recommendation for `"STP"` is `0^"o""C"` `("273.15 K")`, and `"10"^5 "Pa"` `("100 000) Pa")`, which most people write as `"100 kPa"` because its easier to work with, but is identical to `"10"^5 "Pa"`. Using these values, the molar volume of a gas is `"22.710 980 L/mol"`.

So if you are asked to find the volume of a gas at STP, you would use `"273.15 K"` and `"100 kPa"`.

However, many people are still using `0^"o""C"` (`"273.15"`) and `"1 atm"`. Using these values, the molar volume of a gas is `"22.414 L/mol"`.
https://en.wikipedia.org/wiki/Molar_volume

Whichever value you choose to use for STP, make sure the temperature is always in Kelvins (C+273.15), and that the gas constant, R, has the same units that correspond to your temperature and pressure, and be sure you have the correct molar volume if needed.
https://en.wikipedia.org/wiki/Gas_constant

http://en.citizendium.org/wiki/Reference_conditions_of_gas_temperature_and_pressure#cite_note-NISTCODATA-10