In our Freeport air, nitrogen has a partial pressure of 80.0kPa, oxygen 16.0kPa, carbon dioxide 0.3 kPa. We also have water vapor. What is the partial pressure of water vapor in our air if we are at STP? A. 2.0 kPa

B. 5.0 kPa

C. 15 kPa

D. 20. kPa

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%