If 4.61 g of water is sealed in an evacuated 3.35 L flask and heated to the normal boiling point of 373 K,what is the pressure in the flask? (R = 0.08206 L⋅atm/mol⋅K)
A) 0.214 atm
B) 0.428 atm
C) 1.00 atm
D) 2.34 atm
E) 42.1 atm

Question

Quizplus · Accepted Answer

The pressure in the flask can be calculated using the ideal gas law, PV = nRT, where P is the pressure, V is the volume, n is the number of moles of gas, R is the ideal gas constant, and T is the temperature. First, calculate the number of moles of water (H2O) vapor: mass (m) = 4.61 g, molar mass of H2O = 18.015 g/mol, so n = m/M = 4.61 g / 18.015 g/mol = 0.256 mol. Then, using the ideal gas law: P = nRT/V = (0.256 mol)(0.08206 L⋅atm/mol⋅K)(373 K) / 3.35 L = 1.00 atm.

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