A 5.00-L flask contains nitrogen gas at 25°C and 1.00 atm pressure. What is the final pressure in the flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to -55°C?

Answer 1

Use PV = nRT and solve for n in the flask initially. Then mols N2 added = 2 grams/molar mass N2.
Add to find total n (no of mols), and substitute into a new PV = nRT along with the new conditions and solve for the new pressure. Don't forget that T must be in kelvin.