The density of H₂ gas in a rigid container is 0.117 g/L at 55 °C.What is the pressure of hydrogen in the flask if it is heated to 125 °C? (R = 0.08206 L⋅atm/mol⋅K) A) 0.142 atm B) 0.194 atm C) 1.56 atm D) 1.90 atm E) 3.55 atm

Question

Quizplus · Accepted Answer

First, we must find the initial pressure of the gas using the ideal gas law:

PV = nRT

n/V = density = 0.117 g/L / (2.016 g/mol) = 0.058 mol/L

P1 = (0.058 mol/L) (0.08206 L⋅atm/mol⋅K) (55 + 273.15 K) = 2.11 atm

We can then use the relationship between pressure and temperature for a fixed amount of gas to find the new pressure at the higher temperature:

P1/T1 = P2/T2

P2 = P1 (T2/T1) = 2.11 atm (398.15 K / 328.15 K) = 2.57 atm

However, this is the total pressure in the container, and we are only interested in the pressure of hydrogen gas. We can use the mole fraction of hydrogen to find its partial pressure:

X(H2) = n(H2) / n(total) = 2 / 3

P(H2) = X(H2) P(total) = (2 / 3) (2.57 atm) = 1.71 atm

Therefore, the answer is D) 1.90 atm (rounded to two significant figures).

The Density of H2 Gas in a Rigid Container Is

The Density of H₂ Gas in a Rigid Container Is