The decomposition of NH$_3$ on a platinum surface, $2\mathrm{NH_3(g)}\xrightarrow{\mathrm{Pt}}\mathrm{N_2(g)}+3\mathrm{H_2(g)}$, is a zero order reaction with k = $2.5\times10^{-4}$ mol L$^{-1}$ s$^{-1}$. What are the rates of production of N$_2$ and H$_2$?

CBSE Class 12 · 2008 · Delhi · Chemical KineticsShort Answer

The decomposition of NH

_{3}

on a platinum surface,

2 N H_{3} (g) Pt N_{2} (g) + 3 H_{2} (g)

, is a zero order reaction with k =

2.5 \times 1 0^{- 4}

mol L

^{- 1}

^{- 1}

. What are the rates of production of N

_{2}

and H

_{2}

Answer: d[N₂]/dt = 2.5 × 10⁻⁴ M s⁻¹; d[H₂]/dt = 7.5 × 10⁻⁴ M s⁻¹.

For a zero order reaction the rate of reaction equals the rate constant:

Rate = - \frac{1}{2} \frac{d [ N H _{3} ]}{d t} = \frac{d [ N _{2} ]}{d t} = \frac{1}{3} \frac{d [ H _{2} ]}{d t} = k

Rate of production of N

_{2}

\frac{d [ N _{2} ]}{d t} = k = 2.5 \times 1 0^{- 4} mol L^{- 1} s^{- 1}

Rate of production of H

_{2}

\frac{d [ H _{2} ]}{d t} = 3 k = 7.5 \times 1 0^{- 4} mol L^{- 1} s^{- 1}

CBSE Class 12 Board · 2008 · Delhi · Subjective