A steel container with a volume that cannot change is filled with 123.0atms of compressed air at 20.0°C. It sits out in the sun all day, and its temperature rises to 55.0°C. What is the new pressure?

(P1/T1) = (P2/T2)

Remember T must be in kelvin.

To find the new pressure of the compressed air in the steel container, you can use the ideal gas law equation, which states:

PV = nRT

Where:
P is the pressure,
V is the volume,
n is the number of moles of gas,
R is the ideal gas constant (0.0821 L.atm/mol.K), and
T is the temperature in Kelvin.

First, let's convert the temperatures from Celsius to Kelvin. To do this, you'll need to add 273.15 to each temperature value.

Initial temperature (T1) = 20.0°C + 273.15 = 293.15 K
Final temperature (T2) = 55.0°C + 273.15 = 328.15 K

Now, we have the initial pressure (P1) as 123.0 atm, volume (V) that does not change, and the initial and final temperatures (T1 and T2). We need to find the final pressure (P2).

Using the ideal gas law equation, we can rewrite it as:

P1/T1 = P2/T2

Now, let's plug in the values:

123.0 atm / 293.15 K = P2 / 328.15 K

To find P2, we can cross multiply and solve the equation:

P2 = (123.0 atm * 328.15 K) / 293.15 K

P2 = 138.07 atm

Therefore, the new pressure of the compressed air in the steel container after it heats up to 55.0°C is approximately 138.07 atm.