At a particular temperature the first-order gas-phase reaction n 2o 5→ 2no 2 + (1/2)o 2 has a half-life for the disappearance of dinitrogen pentoxide of 5130 s. suppose 0.450 atm of n 2o 5 is introducted into an evacuated 2.00 l flask. what will be the total gas pressure inside the flask after 3.00 hours? a. 0.969 atm b. 0.105 atm c. 0.795 atm d. 1.14 atm e. 0.864 atm

B. 0.105 atm

Explanation:

Let's consider the following first-order reaction.

N₂O₅ → 2NO₂ + 1/2 O₂

We can find the pressure of N₂O₅ at a certain time t using the following expression.

where,

is the initial pressure

k is the rate constant

Given the half-life (t1/2), we can calculate k using the following expression.

k = ln 2 / t1/2 = ln 2 / 5130 s = 1.351 × 10⁻⁴ s⁻¹

When t = 3.00 h (10,800 s),