I've tried everything to figure out how to do this chemistry problem, please help me?

Question

When 23.0 g of the mineral fluorite (CaF2) reacts with excess sulfuric acid, hydrogen fluoride gas is collected at 744 torr and 25.5°C. Solid calcium sulfate is the other product. What gas temperature is required to store the gas in a 7.90 L container at 885 torr?

Answer 1

23.0 grams of CaF2 is 0.295 moles of CaF2 (MW CaF2 = 78). Given that you use excess sulfuric acid, you would produce 0.590 moles of HF gas.

At this point, you don't need the 744 torr and 25.5 degrees C, as you have the number of moles. Use the Ideal Gas Law to figure out the temperature using the second set of conditions. 885 torr is 1.16 atm.

PV = nRT
T = PV/nR = 1.16 atm * 7.90 L/ (0.590 moles * 0.08206)
T = 189 K = -84 C