A sample of N2O gas has a density of 2.95 g/L at 298 K. What must be the pressure of the gas?

➡PV = nRT

➡PV = (W/M)RT

➡PM = (W/V)RT

➡PM = PRT

➡P = pRT/M

➡P = 2.85 × 0.082 x 298 / 44

➡P = 1.583 atm

➡P = 1.583 × 760

➡P = 1203 mm Hg

Hope this helps you:)

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%