The volume of a gas is 36.0 ml at 10.0°c and 4.50 atm. at what temperature (°c) will the gas have a pressure of 3.50 atm and a volume of 85.0 ml?

Using the combined gas law, where PV/T = constant, we first solve for PV/T for the initial conditions: (4.50 atm) (36.0 mL) / (10.0 + 273.15 K) = 0.57213.

Remember to use absolute temperature.

For the final conditions: (3.50 atm) (85.0 mL) / T = 297.5/T

Since these must equal, 0.57213 = 297.5/T

T = 519.98 K

Subtracting 273.15 gives 246.83 degC.