Final answer:
To find the final pressure of a gas with unknown initial conditions, we require more data. We would use the combined gas law if the temperature also changes, otherwise we could apply Boyle's Law for constant temperature.
Step-by-step explanation:
To find the final pressure of a gas that started at 273K and was compressed to 1.5L at 1ATM, we can use the combined gas law, which states that the product of pressure (P), volume (V), and temperature (T) of a fixed amount of gas is constant, provided the amount of gas remains unchanged. This law is mathematically represented as (P1V1/T1) = (P2V2/T2). However, since the initial temperature and final conditions are not provided in full, we cannot calculate the final pressure without additional information. Assuming the initial volume and pressure were known, and the temperature was held constant, Boyle's law (P1V1 = P2V2) could be used to find the final pressure when volume decreases.