Question

The decomposition $N{H}_3$ gas on a heated tungsten surface gave the following results:

Initial pressure (mm)	65	105	y	185
Half-life (sec)	290	x	670	820

Calculate approximately the values of x and y.

• A. x = 410 sec, y = 115 mm
• B. x = 467 sec, y = 150 mm
• C. x = 490 sec, y = 120 mm
• D. x = 430 sec, y = 105 mm

Answer 1

Answer: (B)

x = 467 sec, y = 150 mm

$t_{1/2}\alpha P^{1-n}$

$\frac{290}{820}=\frac{65}{185}$, Which Implies

$1-n=1$

$n=0$

$k=\frac{\left[P_0\right]}{2t_{1/2}}$

$k=0.112mol{L}^{-1}{t}^{-1}$

$x=\frac{105}{2\times 0.112}$ = $467sec$

$y=0.112\times 2\times 670$ = $150mm$