Final answer:
To find the original temperature of the gas, we use Gay-Lussac's law and the given pressures and final temperature to calculate that the original temperature was 240 Kelvin.
Step-by-step explanation:
The student's question involves the relationship between pressure and temperature of a gas, which can be understood using Gay-Lussac's law of combining volumes. This law states that for a given mass and constant volume of an ideal gas, the pressure exerted on the sides of its container is directly proportional to its absolute temperature. Using this law, we can set up a proportion since the volume and the amount of gas are constant:
P1/T1 = P2/T2
where P1 and T1 are the initial pressure and temperature, and P2 and T2 are the final pressure and temperature. Given that P2 is 1.5 atmospheres and T2 is 300 Kelvin, and the original pressure P1 was 1.2 atmospheres, we can solve for T1 as follows:
T1 = (P1 × T2) / P2
T1 = (1.2 atm × 300 K) / 1.5 atm
T1 = 240 K
So the original temperature of the gas was 240 Kelvin.