The first-order decomposition of phosphene to phosphorus and hydrogen, shown below, 4PH₃(g) $\rarr$ P₄(g) + 6H₂(g)
Has a half-life of 35.0 s at 680°C.Starting with 520 mmHg of pure phosphene in an 8.00-L flask at 680°C, how long will it take for the total pressure in the flask to rise to 1.000 atm?

Question

The first-order decomposition of phosphene to phosphorus and hydrogen, shown below, 4PH₃(g)

\rarr

P₄(g) + 6H₂(g)
Has a half-life of 35.0 s at 680°C.Starting with 520 mmHg of pure phosphene in an 8.00-L flask at 680°C, how long will it take for the total pressure in the flask to rise to 1.000 atm?

Quizplus · Accepted Answer

The reaction is first-order, so the half-life is constant. The initial pressure of PH3 is 520 mmHg, and the total pressure will rise to 1 atm (760 mmHg). The increase in pressure is due to the formation of P4 and H2. Using the stoichiometry of the reaction and the half-life, the time required for the pressure to reach 1 atm is calculated to be approximately 48.3 seconds.

The First-Order Decomposition of Phosphene to Phosphorus and Hydrogen, Shown →\rarr→

The First-Order Decomposition of Phosphene to Phosphorus and Hydrogen, Shown $\rarr$