1. Convert Units

* Temperature: Convert Celsius to Kelvin: 128 °C + 273.15 = 401.15 K

* Pressure: Leave pressure in atmospheres (atm)

2. Ideal Gas Law

The ideal gas law is: PV = nRT

Where:

* P = pressure (atm)

* V = volume (L)

* n = number of moles

* R = ideal gas constant (0.0821 L⋅atm/mol⋅K)

* T = temperature (K)

3. Rearrange and Solve for Volume (V)

* V = (nRT) / P

4. Plug in the Values

* V = (5.6 mol * 0.0821 L⋅atm/mol⋅K * 401.15 K) / 9.4 atm

5. Calculate

* V ≈ 19.8 L

Therefore, 5.6 moles of sulfur hexafluoride gas will occupy approximately 19.8 liters at 128 °C and 9.4 atm.