The correct answer is 1.5 atm.
Since the temperature stays constant, we can use Boyle's Law:
P1 x V1 = P2 x V2
First, let's look at the oxygen:
Oxygen starts at 1.0 atm in a 1.0 L container. Since its final volume is also 1.0 L, its pressure stays at 1.0 atm.
Now, let's look at the nitrogen:
Nitrogen starts at 1.0 atm in a 0.50 L container. When it enters the 1.0 L container, its volume doubles, so its pressure is cut in half to 0.50 atm.
Finally, Dalton's Law tells us to add the pressures of the two gases:
1.0 atm + 0.50 atm = 1.5 atm
Final answer: 1.5 atm
Think of it this way: Each gas contributes its own pressure to the container. Oxygen contributes 1.0 atm, and nitrogen contributes 0.50 atm. Adding them gives us the total pressure of 1.5 atm!
